The Baths of Caracalla were Roman public baths, or thermae, built in Rome between 212 and 216 AD, during the reign of the Emperor Caracalla. The extensive ruins of the baths have become a popular tourist attraction.
The bath complex covered approximately 13 hectares (33 ac). The bath building was 228 meters (750 ft) long, 116 meters (380 ft) wide and 38.5 meters (125 ft) estimated height, and could hold an estimated 1,600 bathers.
The Caracalla bath complex of buildings was more a leisure centre than just a series of baths. The "baths" were the second to have a public library within the complex. Like other public libraries in Rome, there were two separate and equal sized rooms or buildings; one for Greek language texts and one for Latin language texts.
The baths consisted of a central 55.7 by 24 meter (183x79 ft) frigidarium (cold room) under three 32.9 meter (108 ft) high groin vaults, a double pool tepidarium (medium), and a 35 meter (115 ft) diameter caldarium (hot room), as well as two palaestras (gyms where wrestling and boxing was practiced). The north end of the bath building contained a natatio or swimming pool. The natatio was roofless with bronze mirrors mounted overhead to direct sunlight into the pool area. The entire bath building was on a 6 meter (20 ft) high raised platform to allow for storage and furnaces under the building.
The libraries were located in exedrae on the east and west sides of the bath complex. The entire north wall of the complex was devoted to shops. The reservoirs on the south wall of the complex were fed with water from the Marcian Aqueduct.
The building was heated by a hypocaust, a system of burning coal underneath the ground to heat water provided by a dedicated aqueduct. It was in use up to the 19th century.
In the early 20th century, the design of the baths was used as the inspiration for several modern structures, including Pennsylvania Station in New York City and National Assembly Building in Dhaka, Bangladesh.
The ruins stand as the backdrop for the Teatro dell'Opera di Roma in the summer opera season. It has also become a venue for modern cultural events, such as the gymnastics competition during the 1960 Summer Olympics in Rome and the concert of the Three Tenors at the conclusion of the 1990 FIFA World Cup.
The baths are open to the public on payment of a small charge, which does not apply to students or pensioners. Access is limited to certain areas to avoid damage to the mosaic floors, although such damage is already clearly visible.

In the 4th century, Emperor Valentinian was cured at the shrine of Caesarius at Terracina, the site of his martyrdom. The emperor then decided to move his relics to Rome. They were taken to a church on the Palatine, and when they were later moved to a new church, that church got the name "in Palatio", "at the Palace". It is also known as San Cesareo de Appia.
Excavations have revealed foundations of what is thought to be the first church here, built in the 8th century. The first time the church is mentioned in written sources is in 1192, so nothing is known about the early period.
In the Middle Ages, the church was part of a hospice and hospital for pilgrims.
The present church is the result of Pope Clement VIII's rebuilding in 1602-1603, carried out under Cesare Cardinal Baronio's instructions. Baronio was a historian of the Church, and was interested in restoring the church to its original state. It was restored in the years 1955 to 1963.
Next to the church is a medieval house where Cardinal Baronius, who restored Santi Nereo e Achilleo, lived when he was titular of San Cesario. It is sometimes open to the public - check if you are interested. The Renaissance façade was designed by Giacomo della Porta. It was decorated with frescoes in the 1602-1603 rebuilding, but these have since disappeared through erosion.
The column in front of the building was used as a sign in the Middle Ages, showing that the church was a centre for pilgrims.
The Cosmatesque furniture here may have been brought here from San Giovanni in Laterano, although it may also have come from other churches, when the transepts there were restored in the early 17th century. It includes the pulpit, the balustrades, a frontal to the altar and an episcopal chair behind the altar. Note the pale blue colour, which is unusual in Cosmatesque work.
The paintings between the windows are by Cavaliere d'Arpino and Cesare Rosetti in the 17th century. They depict the martyrdoms of St Caesarius and several saints named Hippolytus. The latter were included as a compliment to Pope Clement VIII, who was baptized as Ippolito.
The motif in the coffered ceiling is Clement VIII's coat-of-arms (the Aldobrandini family), and St Caesarius is depicted in the central panel.
The fresco of the Blessed Virgin hanging above the bishop's chair is from the 15th century.
In the apse is an uncommon motif in the mosaic, God the Father made from a design by Cavalier d'Arpino in the 16th century.
Excavations below the church have revealed a Roman bath from the 2nd or 3rd century. If you ask the custodian, he will open a door leading to the huge black and white mosaic depicting Neptune and marine creatures.

Originally called Porta Appia, the name is likely to have changed during the mediaeval times, due to the famous catacombs dedicated to St.Sebastian, located about 2 Km. south of this spot.
The gate stands along the famous via Appia, an important roman road, still in use today. Its first 7 km. - 4 miles are accessible to cars, and a few traces of the original stone paving can be seen along the way; outgoing traffic is then diverted towards via Appia Nuova, the New Appian way, coming from Porta San Giovanni, while the few further remains of the original roman road gradually fade as they enter the countryside.
Porta San Sebastiano's structure is not very different from the small Porta Latina, but the overall look is surely more massive. Also in this case, some alterations to the original roman gate were carried out by Honorius in the 5th century, such as the reduction of the two original archways to a single passage, likely for safety reasons.
Porta San Sebastiano incorporates the so-called Arch of Drusus (or Arco di Druso), a marble decorated arch of the Aqua Antoniniana aqueduct over the Via Appia, wrongly identified with the arch said by the sources to have been erected on the death of Nero Claudius Drusus (the father of Claudius) in 9 BC.

St. Silvia, mother of Pope Gregory I, had built a chapel in her house. In 645, the monks from the monastery of Mar Saba (Palestine) settled in this house, and devoted it to the celebration of St. Sabas. In 768, Antipope Constantine II was held prisoner in this monastery, before being killed by the Lombards. The church was one of the most prestigious of Rome in that era, as its monks probably held diplomatic roles in the relationships between Rome and Byzantium.
The Benedictine of Monte Cassino received the church after its rebuild in the 10th century. After many years of decay, it was completely renovationed in the 13th century, after the church was granted to the Cluniac monks. Before going to the Society of Jesus, the church was granted to the Cistercians in the 15th century.
The church, preceded by a small porch from the 13th century, has a nave with two aisles. These end with three apses. The interior is characterized by numerous interventions from different ages. The columns are from ancient buildings, and the floor is an example of Cosmatesque marble art from the beginning of the 13th century. The main artpieces are the notable frescoes in a room on the left side of the church, the so-called fourth nave: they portrays the miracles of St. Nicholas.
The crypt, built on the house of St. Silvia, holds the relics of St. Sabas. The sacristy houses also a fragment of fresco from the very first church (7th century).
Remains of the Chapel of St Silva were found in 1909, below the church. You may ask the sacristan to let you in.