The ancient site includes the stadium where most Olympic Games took place during antiquity, held every four years for nearly a thousand years. The racetrack is over 656 feet long. The Olympic flame is still lit here for modern day Games at the altar of the temple built dedicated to the goddess Hera in the 7th century BC. Visitors can also view the Temple of Zeus near the stadium, which was made of marble and lime. The Philippieion is considered one of the finest examples of ancient Greek architecture and is the only circular building inside the sanctuary. Just west of the Altis enclosure is Palaestra, constructed in the 3rd century BC, part of the gym complex where people once practiced wrestling, boxing and jumping.