Close to one of the city's main bus terminals in Dikasterion Square lies the archaeological site of the ancient Greek agora or marketplace, which was later expanded to become a Roman Forum on two levels. The Roman Forum was constructed in the late 2nd century AD and it constituted the administrative centre of the town till about the 5th century. The forum was the heart of the ancient city, and was discovered by workmen in the 1960s. The best-preserved component of the forum is the large theatre, which is still used for occasional summer concerts. On the southwest corner of the square is the magnificent church of Panagia Chalkeon. The Archaeological Museum built beneath the ruins houses some of the artefacts discovered in excavations on the site and a visit to the museum gives great context for exploring the site. It is small but captivating. Entry to the ruins is free but there are no written explanations, making the museum a necessary stop. The site is closed on Mondays. The area around the excavations is full of artists, shops and taverns and there are some wonderful little places to buy traditional wares and souvenirs.