The Greek historian Herodotus visited the city of Babylon in 460 BC, after it had been conquered by the Persian Cyrus, and stripped or treasures, but when its walls and temples were still standing, and he described the largest city of the ancient world. The entire city was enclosed within a wall from 14 to 10.5 miles on each side (depending on which ancient historian is referenced). The river Euphrates passed through the city walls, and the brick lined channel was lined by waterfront, wharves, and docks along its length inside the city. Each of the four walls were pierced by 25 fortified gates, each guarded by massive bronze gates, through which the 50 thoroughfares of the city passed, forming 625 regular city blocks, each of at least 100 acres. The famous Ishtar Gate was a gated entrance to an inner wall in the city.
The area inside the walls included gardens and farms, as well as buildings and a full size pyramid, all made of bricks and palm wood. The walls enclosed up to 196 square miles! The step pyramid was the temple of Belus. It was 600 feet on each side at the base, and rose to a height of 480 feet, which compares to the 481 feet of the Egyptian pyramid at Giza. Stairs around the pyramid allowed worshipers to travel to the top, to place offerings at the temple there. The view from the top of the city laid out below, with the river, parks, walls, the hanging gardens, and the surrounding agricultural areas would have been in incredible sight to visitors and residents of the great city.
The most impressive structure of the city
might have been the outer walls. Herodotus stated the walls were 85 feet wide, and 335 feet tall, topped by 250 defensive towers. The top of the walls included a road wide enough that a four horse chariot could turn around on the road. The top of the walls were the site of the Hanging Gardens of Babylon, which were watered by a "huge hydraulic machine, working after the manner of the screw of Archimedes", which drew water tot he gardens. The Hanging Gardens of Babylon were one of the Seven Wonders of the Ancient World, which are described in the following links.