In 170 AD, the Telesterion was burnt down by the Cotsoboci, invaders of northern origin. In its reconstruction, in the years of emperor Marcus Aurelius (121-180 AD), the plan of the classical times was kept. In Roman times, moreover, two stairs were cut in the rock that led to an elongated square, 70m long and 11,45m wide (Upper Court), which was created by levelling the rock along the west side.

At the north end of the Upper Court (terrace west of the Telesterion), there are preserved the foundations of a temple that was erected, most probably, in the time of Marcus Aurelius (161-180 AD), to honour the wife of Antoninus Pius, Faustina the Elder, who, after her death, in 140 AD in Rome, was deified and venerated as «New Demeter».

On the hill, east of the temple of Faustina stands the post-Byzantine church of Virgin Mary, built over the ruins of an older church, most probably one of the three early christian basilicas of Eleusis. Today of the older building there are visible only the architectural remains of the east side.

In Roman times buildings were constructed outside the walled area of the Sanctuary. Apart from the public buildings that were meant for accommodating the needs of the worshippers, such as hotels and baths, there also were private ones which were the houses of prominent persons. The best preserved example is the luxurious rectangular two-storey house of the 2^nd cent. AD, on the south slope of the ancient acropolis hill.

The edifice was constructed during the Late Geometric period (end of  8^th cent. BC) on a terrace aligned north-south. It has been considered that it was dedicated to the cult of a hero-ancestor who lived there and for this reason it was characterized as «Sacred House». Most probably the grave that was found east of the house belonged to him.

At the South Pylon of the Sanctuary terminated the road from the harbor and the seaside. This gateway forms part of the south branch of the fortification enclosure, which is preserved almost up to its original height. It is the so-called Lykourgean Fortification, which was built in the 4^th cent. BC to enlarge the Sanctuary on the south side.

Mithraea (Mithraic temples) were gathering places for the followers of the Indo-Iranian in origin god Mithras, the main deity of a mystic cult that flourished in the 2^nd  and  3^rd  cent. BC in the Roman Empire. The cult of Mithras gained numerous and faithful worshippers among the soldiers of the Roman legions who spred it across Europe as they moved in the course of wars.

It is situated in the area outside the Lycourgean enclocure and near the building, which is known as Mithraeum. The foundations of a large rectangular building are visible with peristyle central courtyard, lateral rooms and a small porch on the front. It is dated to Roman times.

Directly adjacent to the outer side of the Lykourgean and Periclean fortification wall there were constructed in Roman times cisterns and fountains to meet the needs of the crowd of worshippers.

In Pericles’ time in the 5^th cent. BC the enclosure wall of the Sanctuary was extended to the east and south, beyond the contour of the Peisistratean enclosure of the 6^th cent. BC. The Periclean wall, as this part is called, is built in the isodomic system and about 4m wide.

In the area outside the east extension of the wall which was considerably reinforced in Roman times, there are preserved remains of buildings of the same period. Their  use is associated with serving the needs of the large number of worshippers who gathered in the Sanctuary.