The East Gate of Serdica-Sredets was part of the town defences in the period 2nd –14th century CE. Its present monumental appearance - featuring stone blocks, two pentagonal towers, a gate with a drawbridge door and internal gate with three passageways - dates back to the time of Emperor Justinian I (527-565 ). In its original form during the first construction of the fortress wall the Gate was a solid structure with three passageways - wide central archway for transport vehicles to pass and two narrow ones on the sides intended for pedestrians. The fortification wall from this period was built of bricks on top of stone block plinth. No significant changes were made to the East Gate during the second major reconstruction of the wall (at the end of the 3rd - start of the 4th century CE). At the time of Emperor Justinian I the Gate was reinforced with two pentagonal towers that guarded a passageway made of solid stone blocks. The passageway between the earlier triple passage gate and the later single passage gate was guarded through two small doors in the pentagonal towers. The East Gate retained its appearance during the Middle Ages except for some minor adjustments.
The first excavations of the East Gate of the ancient town began back in 1966 when the construction of a modern urban underpass was commenced. The 'East Gate' Underpass was officially opened in 1971 following a detailed archaeological research. The Underpass was closed in the period 1993-1999 due to its extremely poor condition. Rehabilitation activities were carried out in 1999, as well as conservation and restoration works on the archaeological monuments, and then the complex was finally reopened.
