A moat is a deep and wide trench around a fortress. The moat can be both empty or filled with water.
Moats are found surrounding fortresses, buildings and cities. Historically, a moat is part of a defense stragety. Some of the most famous moats in Denmark can be found in Copenhagen, at Egeskov Castle and the castles of Vordingborg.
Often a drawbridge could be laid across the moat to allow passage across.
Seen archaeologically moats can be very interesting, as findings found in the moats help illustrate that they had other purposes than just defense.