The original Roman Agora was encroached upon and obstructed by a series of Roman buildings, beginning with the imperial family's gift to the Athenians of a large odeion (concert hall). The Odeon of Agrippa was built by him in around 15 BC, and measured 51.4 by 43.2 metres, rose several stories in height, and – being sited just north of the Middle Stoa – obstructed the old agora. In return for the odeion, the Athenians built a statue to Agrippa at the site of the previous agora; they based it on a plinth recycled from an earlier statue by covering the old inscription with a new one.
After the invasion of the Herulae in AD 267 the city of Athens was restricted to the area within the Late Roman fortification wall, and the administrative and commercial centre of the city was transferred from the Ancient Agora to the Roman Agora and the Library of Hadrian.
During the Byzantine period and the Turkish occupation the area was covered with houses, workshops and churches along with the Fethiye Mosque.
The Tower of the Winds is an octagonal Pentelic marble clocktower that functioned as a horologion or 'timepiece'. It is considered the world's first meteorological station. The structure features a combination of sundials, a water clock, and a wind vane. It was supposedly built by Andronicus of Cyrrhus around 50 BC, but according to other sources, might have been constructed in the 2nd century BC before the rest of the forum.
The Gate of Athena Archegetis is considered to be the second most prominent remain in the site after the Tower of the Winds. Constructed in 11 BCE by donations from Julius Caesar and Augustus, the gate was made of 4 Doric columns and a base of Pentelic marble. It was a monument dedicated by the Athenians to their patroness Athena Archegetis.
The East Propylon is the eastern entrance of the Roman Agora in Athens. Built in 19-11 BCE, it constituted of 4 Ionic columns made of gray Hymettian marble.References:
The Basilica of Santa Maria in Trastevere is one of the oldest churches of Rome. The basic floor plan and wall structure of the church date back to the 340s, and much of the structure to 1140-43. The first sanctuary was built in 221 and 227 by Pope Callixtus I and later completed by Pope Julius I.
The inscription on the episcopal throne states that this is the first church in Rome dedicated to Mary, mother of Jesus, although some claim that privilege belongs to the Basilica di Santa Maria Maggiore. A Christian house-church was founded here about 220 by Pope Saint Callixtus I (217-222) on the site of the Taberna meritoria, a refuge for retired soldiers. The area was made available for Christian use by Emperor Alexander Severus when he settled a dispute between the Christians and tavern-keepers.
The church underwent two restorations in the fifth and eighth centuries and in 1140-43 it was re-erected on its old foundations under Pope Innocent II.