Certain are the datum for the urban planning of the central part of Roman and Early Byzantine Serdica which today lies under Nezavisimost square and the buildings east of it. It is found the town square (forum) to which the main streets with east - west (Decumanus Principalis) direction and north - south (Cardo Principalis) direction lead. They intersect at right angles, something typical for the Roman towns and provinces. From this system branch off a few streets north of TsUM, obvious mark for an older town plan.
Inside the fortified walls there is an encircling - street - intervallum. The widest streets were cardo principalis and decumanus principalis - 9 m (so as the intervallum) - leading to the Gateways. The width of the others varies between 5 and 8 meters. The pavement was made of stone blocks 1.2 - 1.5 meters wide. In the middle of the street was built a covered sewer. Water - main in clay pipes was passing through under the pavement. The street bed was restricted by curb stones made of 50 - 60 centimeters high stone blocks.
It is interesting that the direction of the roman street grid has remained almost unchanged so far. Even the Dondukov Blvd. which seemingly is an exception from that grid actually keeps the direction of an old roman road leading to the eastern gateway.
The remains of an ancient street A with north - south direction are found. Walls of a canal and ancient buildings on street A are revealed in northern direction. The walls and the canal branch off in eastern direction here in new ancient street Б intersecting at right angles with the first one. There is other ancient street B east of TsUM. It is 85 meters long with north - south direction, 5.95 meters = 20 roman steps wide. It has the same structure as streets A and Б. During the excavation is not found the flow of street B into the main street (Via Principalis) which direction is determined when the Eastern gateway is excavated.
East of the described street B are revealed four insulas in the southeastern end of the terrain of the Council of Ministers. They are very close to the fortified wall and the eastern gateway. Most of the terrain east of ancient street B is in the vicinity of the Council of Ministers and remains untouched since it is designed for yard.
The excavated streets Е and Ж haven't got pavements and the buildings on their both sides step directly on the street bed. Their width is different but most of the streets are narrower than the present ones.