Today, you will find the Stadium east of the Altis, after walking past the Echo Stoa with the great Temple of Zeus behind you. However, during the first centuries of the Games, i.e, before the 6th century BC, the running course was nothing but a flat area before the Treasuries. This simple structure gave way to the three following phases of the Stadium, all at the foot of Kronios hill, whose slope provided a natural seating area for the spectators. Stadium I was built in the mid-6th century BC, with one of its short sides facing the altar of Zeus. Stadium II was moved further to the east, with no other architectural elements apart from a 3-metre-high platform, which served as a second seating area in the south, opposite the hill.
After the grand Temple of Zeus was built in the 5th century BC, and the Games reached a peak of popularity, the final Stadium III was built even further to the east, surrounded by banks for the thousands of people attending. As the Games became increasingly secular, the separation of the Stadium from the sanctuary was deemed necessary, therefore the Echo Stoa was built around 350 BC to block the Temple of Zeus from view and provide a boundary between the profane and the sacred. In numbers: the racetrack is 212.54 metres long and up to 34 metres wide, and the starting and finishing lines are indicated by two stone markers set 192.27 metres apart (which corresponds to the ancient unit of length of one Olympic stadion). The Stadium accommodated up to 45,000 people and, even though no permanent seating was provided along the banks, there were stone thrones for officials and guests of honour in the typical fashion of ancient theatres. After the 3rd century BC, athletes entered the Stadium through a vaulted entrance called the Krypte (=Crypt).