1. Baths of Diocletian

The Baths of Diocletian were built by Emperor Diocletian in 302 A.D, and was later turned into the church by Michelangelo. In order to make a better use of solar energy, the Baths were built on the north-south axis, so that the calidarium, or hot bath, faced southwest, and frigidarium, or cold bath faced northeast. The apodyteria or dressing rooms, and other halls which served for private baths were located on each side of the calidarium. Large exedra used as a theater was located in the center of the south-west side. The Baths of Diocletian also contained gymnasiums, art galleries, gardens, libraries, and concert halls. The Baths of Diocletian was the largest Roman baths, it could hold up to 3000 people at once. The central hall of the building was 280 by 160 meters. The exterior of the building was decorated with marble of various colors, painted stucco and statues.

2. Forum of Trajan

The Forum of Trajan (later called Forum Ulpium) was built by Apollodorius. He constructed the Forum experimenting with a variety of the elements, which include the use of concrete, emphasis on light, elaborate and colorful decoration, and the use of curvilinear architecture. The Forum consisted of the Basilica Ulpia, the Column of Trajan, the Bibliotheca, Trajan's Market, and Temple of Trajan, which was built on the north-west side of the bibliotheca by Hadrian after Trajan's death. The Forum of Trajan occupied the area of 300 by 180 meters, with uncovered piazza area 120 by 90 meters. An equestrian statue of Trajan was in the center of the piazza. The forum proper was a rectangular court. The entrance to the area was in the middle of the south-east side, opposite the forum of Augustus. The Basilica Ulpia, which occupied the area of 180 by 60 meters, was located on the north-west side of the area of the forum. Across the north-east wall of the Basilica two libraries were located, one had Greek books, the other one - Latin. The Forum of Trajan was utilized as an area for public ceremonies. For example it is known that in 118 A.D. Adriano publicly burned tables with citizen's debts in the piazza, as a statement to the treasury.

3. Column of Trajan

The column is now the best preserved feature of Trajan's Forum. The Trajan column is 29.77 meters high (100 Roman feet); the height of the column with a pedestal is 38 meters, the diameter 3.7 meters. Originally a statue of the emperor stood on top, but this was lost in the Middle Ages and its place taken by the statue of St Peter in 1588. The pedestal of the column served as the tomb for Trajan's ashes after his death in 117A.D. The sculptural reliefs, which wind in a spiral 23 times round the shaft to a length for approximately 200 meters. Each of the spirals was carved after the column had been erected and is about 3 feet wide. In order to make it possible for the viewer to see the highest spirals, the architect gradually increased the height of the band as it spirals up the Column (0.9m to 1.25m). The relief that contain approximately 2.500 figures in various scenes, depict the major military victories of Trajan in Dacia. The Column commemorates Trajan's successes, but he remains a human figure, not a superman, in scale.

4. Market of Trajan

The Market of Trajan was designed by the emperor's architect Apollodorus of Damascus and built between 94 and 113 CE for the Emperor Trajan. The markets were a commercial center of about 150 shops and offices, set into the side of the Quirinal Hill and completing Trajan's Forum. The markets are the best-known example of modular commercial construction in concrete. It is a complex architectural structure that consisted of six major levels, though the pavements of the few corridors and rooms are located between them. The plan of superposed level is not necessarily vertically congruent with the one below. The careful planning is evident in the relationships between the streets and shops, the functional locations of the stairways and ramps, and the openings that were built to bring adequate lighting and ventilation. The semicircular brick building is set into the hill above which are tiers of terraces ascending the slope. At the upper end of the hill, a two-story market hall with a series of groin vaults was lined with shops on each side of a central promenade with a balcony level and clerestory openings above. The brick facades have brickwork arches and pediments and travertine lintels, and the markets are a good example of concrete and brick construction, with vaults and arches.

5. Temple of Claudius

The Temple of Claudius and the temple court occupy their own insula (city block), the largest insula in town with the exception of the insula of the Basilica and Forum, and that of the town baths. The Temple was almost entirely destroyed by Nero, and rebuilt by Vespasian. The Temple was the pride of city's architecture and a memorial not only to the emperor but also to the heroic people of Rome. The Temple of Claudius sat on a podium rising 20 steps above the plaza. The substructures of the podium were different on the different sides of the podium: on the west side they consisted of double rows of travertine arches with engaged columns and entablature; on the north side they contained something that could have been reservoirs for water; the east side consisted of alternately square and semicircular recesses which were separated from the podium by narrow passages. The recesses were divided from each other by narrow semicircular niches in groups of three. This difference in style and construction was probably due to the combination of temple and nymphaeum, which was the result of Vespasian's restoration. The entrance to the temple court was from the south through a monumental central entrance. A series of piers (brick archways with partly engaged columns) stood around the court, cased with ashlar blocks of shelly limestone. The piers were connected with ornament of plaster work. A gravel footpath led visitor and worshipper from the court entrance to the large outdoor altar, surrounded on three sides by an architectural screen decorated with coloured marbles from all parts of the empire. Equestrian statues of the victorious Emperor Claudius throughout the temple were placed on high pedestals.

6.Circus Maximus

Circus Maximus was the first known Roman circus. It was built during the Etruscan period in the sixth century BCE for chariot racing. The circus was first built out of wood. Then it was destroyed by fire twice and rebuilt a few times. In 363 BCE, the Tiber River was flooded and the Circus was inundated. The Roman started to build gates in 329 but it didn't help much. Therefore, there were a few more floods in the Circus's records. In 196, an arch (fornix) was built in the Circus by Lusius Stertinius. About 2 years later, an order had been sent by the censors for the Roman Games that the senators and common people had to sit separately. So the seats had been modified in the Circus in order to meet the requirement. Also, an enormous stage was built in 167 for flute players, scenic artists and dancers. Now, the only visible parts of the ancient structure are at the semicircular end on the palatine side. The excavations in 1930s had exposed the seating tiers' substructures in that area.

7. Aqueduct

The Romans used aqueduct as part of a supply system to bring water from the mountain springs to the cities. Rome's first aqueduct was built in 312 BCE, and by the period of Emperor Trajan, there were eight aqueducts supplying water everyday in Rome. Water was conducted down to a reservoir by aqueduct - channels or ducts that lined with hard waterproof cement and slabs of stone. Two or three tiers of great arches set on piers supported the aqueduct to cross ravines and rivers. Hills would be tunneled thought if they were in the way. Stone, brick and concrete were used to build the arches and piers. Pipes that were made with lead, wood or terracotta connected public fountains from the reservoirs. People could collect water from the public fountains, and usually the wealthy families laid water pipes to their own houses. Water was also supplied to the baths. But the lead water pipes the Romans used may effect on their health. Consuming too much lead may cause stroke, cancer, and kidney disease. Now, some of the aqueducts still exist. Such as the one in Segovia and Pisa.

8. Forum of Augustus

The forum of Augustus was built by Augustus. It served the needs for additional rooms for the courts and the increasing population. Augustus purchased the land at enormous expense from the spoils of war. His original plan for the forum did not succeed, since he could not acquire enough land. The forum was not dedicated until 2 BCE due to the delays. The size of the area complex is 125 by 118 meters. The height of the forum walls is 33 meters. Now, there are fragments and a few columns still standing at the site.

9.Temple of Augustus

The temple of Augustus was constructed between the year 2 BCE and 14 AD at the highest point of the city. The temple is 14 meters high and 8m wide. It was built by Tiberius, or by Tiberius and Livia. According to Suetonius (?), the temple wasn't finish by Tiberius, but Caligula completed it. On the other hand, Tacitus said that the temple was actually finished by Tiberius finished the temple, but it wasn't dedicated for some reason. In 79 AD (?), Domitian restored the temple since it was destroyed by fire. Then a bomb almost destroyed it again in 1944, and it was reconstructed in 1945-1947. Also, the temple had been used as a church, wheat storage, and now there is an exhibition inside with a collection of ancient stone and bronze sculptures.

10. Arch of Titus

The arch of Titus is the oldest surviving arch in Rome. It was built to celebrate the victory of Vespasian and Titus against Jews in 71. The construction was completed by Titus' brother, Domitian. The arch is 15.40 meters high, 13.5m wide, and 4.75m deep. While the archway is 8.30 meters high and 5.36m wide. Pentelic marble was used to construct the arch. Corinthian columns are standing on square pedestals on each side. Composite style was used for the capitals of the columns. There is a small frieze represented the triumphal procession in the center of the eastern side. There are also two large panels on the inside of the arch. The one on the southern side shows the transportation of the spoil from the Temple of Jerusalem, such as the seven-branched candlestick and the silver trumpets. The relief on the northern side illustrates Titus was crowned while he passed through a triumphal arch. Roma was leading four horses with Titus standing his chariot. Now, the arch of Titus is still standing at good shape in Rome.

11. Arch of Constantine

After the battle at Milvian Bridge in 315 AD, Constantine built the arch that learns his name to commemorate his defeat of Maxenitus. There are three passageways on the arch. The arch is 21 meters high, 25.7m wide, and 7.4m deep. While the central archway is 11.5 meters high and 6.5m wide, and the side archways is 7.4 meters high and 3.36m wide. The arch stands at the start of the road near the west side of the Colosseum. The road leads south between the Palatine and Caelian Hills to the Circus Maximus. There are eight Dacian barbarian statues on the arch. On the western side, there are reliefs of Victories, Seasons and River Gods in the spandrels of the arches. Also, there are reliefs on the column base with Victories, soldiers and barbarian captives. Reliefs of Emperor Marcus and Aurelius are on the northern side as well. The arch of Constantine is standing still right next to the Colosseum recently.

12. The Palatine Hill

The Palatine Hill was a place where many emperors and the rich lived. It is located between the Forum Romanum, the Velabrum and the Circus Maximus. People started living on the Palatine Hill in 753 BCE. Different kinds of buildings were built on the hill, such as Stadium of Domitian, where he held private hunts, games and fights. The Farnese Gardens which were done by Renaissance architect Vignola for the Cardinal Alessandro Farnese. Also, the House of Livia was built on the Palatine hill. This was the house for Emperor Augustus's wife. People believe that Augustus had lived in the house as well. Now, there are mostly ruins of temples and houses left on the Palatine hill.

13. Mausoleum of Augustus:

The Mausoleum of Augustus, which was built in 25 BCE, served as a tomb for Augustus and his family in Rome. The first person buried there was Marcellus, the emperor's nephew, who died in 23 BCE. Consequently, an old rule was broken that forbade burial within city limits. The essential form of the Mausoleum was inspired by the Etruscan tumulus. It resembles a birthday cake with thin cypress trees planted on the first layer like candles. The base of the tomb was circular measuring 88 meters in diameter. Radial walls forming five spiral rings created the structure. The outer walls were made of concrete and covered by travertine opus quadratum 12 meters high. The inner radial walls were also made of concrete, although fronted with opus reticulatum. Originally fashioned with white marble, the tomb covers over two acres. Inside, family members occupied a ring of niches that surrounded the funeral room. In the center is a smaller room where Augustus himself was buried. In his honor, a bronze statue of Augustus rested atop the tomb. During the twelfth century, the Colonna family occupied the tomb as a fortress. After suffering many devastations, it finally was restored in 1939.

14. Pantheon

Called the "greatest and most perfect of the circular temples," the Pantheon was originally built in 27 BCE by Agrippa, the son-in-law of Augustus. Emperor Hadrian rebuilt the temple from 118 AD to 128 AD. The purpose of the building is suggested by the name itself. The word pantheon means "all gods." Whereas other temples were constructed for the worship of one god, the Pantheon was dedicated to all deities. Recesses around the circular walls were reserved for statues of various gods. As the protecting deities of Agrippa's family, Mars and Venus were honored with the most distinguished positions on the temple. Agrippa's Pantheon was considerably smaller than the one built later by Hadrian. The former measured 19.8 x 43.5 meters and would have almost been able to fit inside Hadrian's Pantheon. The floor and dome supporting walls were covered with colored marble. The dome itself was made of concrete. It was the largest of its kind for over a thousand years, and remains the biggest dome constructed of mass concrete. At the top center of the dome is the oculus, where light passed through and lit the interior. Originally, bronze sheeting covered the outside of the dome. However, it was replaced with lead in the eighth century. In 608 CE, the temple was presented to Pope Boniface VII by Emperor Phocas. It was re-dedicated as the church of Santa Maria and Martyres and has been used that way since. Many restorations have been made, including those made to part of the upper walls which were restored to its original design.

15. Colosseum

Originally called the Flavian Amphitheater, the Colosseum was dedicated in 80 CE. Construction began ten years earlier by Vespasian and continued by his sons Titus and Domitian. It was the first permament amphitheater built in Rome. It was renamed "the Colosseum" because of its nearness to the enormous statue of Nero, Colossus Neronis. To mark its inauguration, the amphitheater was dedicated by Titus with one hundred days of games. It became the center of entertainment in the city Rome, exhibiting vicious gladitorial battles and brutal fights between men and wild animals. Some consider that the completion of amphitheater came during Domitian's rule with the addition of the upper levels, which were made of brick-faced concrete. A combination of construction methods was used for other parts including travertine for the piers and arcades, tufa for the lower level walls, and concrete for the foundations. A fence with wooden rollers was constructed around the arena to prevent the animals from reaching spectators. The floor of the amphitheater was also made of moveable wooden sections. These allowed for an easier way of changing the scenery of the arena. Lifting devices were also used to bring animals up to the arena floor. The amphitheater was designed to seat up to 50,000 spectators. The Colosseum is an immense ellipse measuring 617 by 512 feet. The arena area measured 289 by 180 feet. The base of the building spans approximately six acres. There are eighty radial walls which support tiers of seating, passageways, and stairs. Three tiers of arches and an attic story roughly equal the height of a 15 story building - 158 feet.

16. Temple of Satur

The Temple of Saturn is considered one of the oldest sacred places in Rome. Erected in 498 BCE, the temple was dedicated to Saturn, the mythical "god-king" of Rome. The celebration was held each year in his honor from December 17 to 23. During this week of festivities, people exchanged gifts, and the Roman citizens socialized with the slaves. Many of these traditions were carried on by the Christians as this celebration eventually grew into Christmas. The building itself would later be used as a public treasury. Included was an underground chamber where treasures were kept. The temple was restored and enlarged in 42 BCE, and again in the 4th century following a fire. The columns contain partly monolithic granite shafts. The eight remaining columns date back to the first restoration and are often described as among the most dramatic ruins standing today. The ruins of the Temple of Saturn are of the most recognizable from ancient Rome.

17. Theater of Marcellus

Dedicated in 13 BCE, what is known as the Theater of Marcellus was based on an idea of Julius Caesar. He had just defeated and killed Pompey, who had built a grand theater, and Caesar wanted to build one even more magnificent. However, his murder ended all plans for the theater. It wasn't until 22 BCE, during the reign of Augustus, that construction began. After nine years of building, the theater was finally erected. It was named after Augustus' nephew, Marcellus, who died before construction started. The theater was true to Caesar's original conception. It was larger and more elegant than Pompey's theater. The Theater of Marcellus was approximately 50 meters high. The seating area stretched to a length of 130 meters in diameter, accommodating up to 14,000 spectators. It was completely covered in white travertine and was mostly constructed of tufa, cement, and opus reticulum brickwork. Through the centuries, a number of emperors, including Nero, Vespasian, and Alexander Severus, have made numerous restorations and repairs on the theater. In addition, it underwent various uses. In the twelfth century, the Savelli family turned it into a fortress. In spite of all of its transformations, the Theater of Marcelllus remained the biggest ever built in the Roman Empire.