The stadium is located further up the hill, beyond the via sacra and the amphitheatre. It was originally built in the 5th century BCE but was altered in later centuries.
The last major remodelling took place in the 2nd century CE under the patronage of Herodus Atticus when the stone seating was built and arched entrance entrance. It could seat 6.500 spectators and the track was 177 metres long and 25.5 metres wide.
From Wikipedia
http://en.wikipedia.org/wiki/Delphi
Text is available under the terms of the GNU Free Documentation License
http://en.wikipedia.org/wiki/Wikipedia:Text_of_the_GNU_Free_Documentation_License
