Preveza is a town in the region of Epirus, northwestern Greece, located at the mouth of the Ambracian Gulf. It is the capital of the regional unit of Preveza, which is part of the region of Epirus. The Aktio-Preveza Immersed Tunnel, the first and so far only undersea tunnel in Greece, was completed in 2002 and connects Preveza to Aktio in western Acarnania in the region of Aetolia-Acarnania. The ruins of the ancient city of Nicopolis lie north of the city.