Gytheio, the ancient Gythium or Gytheion, is a town and a former municipality in Laconia, Peloponnese, Greece. Since the 2011 local government reform it is part of the municipality East Mani, of which it is a municipal unit. It was the seaport of Sparta, some 40 km north. Gytheio used to be an important port until it was destroyed in 4th century AD, possibly by an earthquake. Today it is the largest and most important town in Mani. It is also the seat of the municipality of East Mani.