The Elenska Basilica or Elensko Basilica (Bulgarian: Еленска базилика, Elenska bazilika) is a large partially preserved late Roman (early Byzantine) Christian basilica in west central Bulgaria. Dating to the 5th–6th century AD, it lies 5 to 6 kilometres (3.1 to 3.7 mi) northeast of Pirdop and 3 kilometres (1.9 mi) from Anton, on the right bank of the Elenska (or Elensko) River (Еленска река, Elenska reka). The initially domeless basilica, which features thick walls and defensive towers, had a dome added in the mid-6th century, during the reign of Justinian I. The church was ruined in the early 18th century, during the Ottoman rule of Bulgaria.