The Great Basilica of Pliska (Bulgarian: Голяма базилика в Плиска, romanized: Golyama bazilika v Pliska) is an architectural complex in Pliska, the first capital of the First Bulgarian Empire, which includes the cathedral, an archbishop’s palace and a monastery. The basilica was constructed on the orders of the knyaz of Bulgaria, Boris I (r. 852–889), after his baptism in 864 and the resultant Christianization of Bulgaria. Completed around 875, the basilica was 102.5 metres (336 ft) long and 30 metres (98 ft) wide. The complex includes Great Basilica itself – a basilica used as the cathedral church – and the attached monastery and episcopal palace inhabited by Christian monks and the bishop of Pliska.
Source: Wikipedia
