Kozloduy (Bulgarian: Козлодуй) is a town of 13,871 inhabitants in northwest Bulgaria, located in Vratsa Province, on the river Danube. The city was liberated from Ottoman rule on 23 November 1877 by the Romanian Army under the command of the Imperial Russian Army. Kozloduy is best known for the Kozloduy Nuclear Power Plant, Bulgaria's only (as of January 2011) nuclear power plant, which is situated nearby, as well as the second largest Bulgarian Danubian island, Kozloduy Island. The city is also famous for the "Radetski" ship, the boat in which the poet/revolutionary Hristo Botev and with 200 others crossed the Danube River in a final attempt to gather an army and liberate Bulgaria from the Ottoman Empire.

The earliest official data shows that Kozloduy was populated in the 1500s. It is in the burial mounds where traces of a Thracian dwelling center that existed in the first millennium B.C. remain^{[citation needed]}. Later on the big Roman roadway along the Danube passed through these places. The remains of the Roman castella (i.e. castles) Magura piatra (or Regianum), Camistrum and Augusta testify to this. In this region there are three historic trenches which were later called Lomski, Ostrovski and Kozloduiski where a military garrison of Khan Asparukh was placed.