The basic framework of the city consists of two large semicircles about  in diameter. The city was designed as a circle about  in diameter, leading it to be known as the "Round City". The original design shows a single ring of residential and commercial structures along the inside of the city walls, but the final construction added another ring inside the first. Within the city there were many parks, gardens, villas, and promenades. There was a large sanitation department, many fountains and public baths, and unlike contemporary European cities at the time, streets were frequently washed free of debris and trash. In fact, by the time of Harun al-Rashid, Baghdad had a few thousand hammams. These baths increased public hygiene and served as a way for the religious to perform ablutions as prescribed by Islam. Moreover, entry fees were usually so low that almost everyone could afford them. In the center of the city lay the mosque, as well as headquarters for guards. The purpose or use of the remaining space in the center is unknown. The circular design of the city was a direct reflection of the traditional Persian Sasanian urban design. The Sasanian city of Gur in Fars, built 500 years before Baghdad, is nearly identical in its general circular design, radiating avenues, and the government buildings and temples at the center of the city. This style of urban planning contrasted with Ancient Greek and Roman urban planning, in which cities are designed as squares or rectangles with streets intersecting each other at right angles.