Megas Gialos is a seaside village located on the southern side of the island of Syros and between the settlements Posidonia and Vari.
The village has a large beach and some smaller ones. In the area there are hotels, restaurants and a large number of holiday homes.
Next to the beach is the chapel of Agios Antonios. On the opposite side of the bay is the old chapel of Agia Thekla. At the top of the hill above the settlement, there is the chapel of St. John the Baptist. Behind Agios Antonios there is a path leading to the bay of Ambelas, where there is a small and quiet sandy beach.