Lake Copais, also spelled Kopais or Kopaida (Ancient Greek: Κωπαΐς; Greek: Κωπαΐδα), was a lake in the centre of Boeotia, Greece, west of Thebes. It was first drained in the Bronze Age,[1][2][3] and drained again in the late 19th century. It is now flat dry land and is still known as Kopaida. A one-time island in the lake was modified in ancient times into a megalithic citadel, now called Gla.