Pliksa and Presla
Pliksa was the first capital of the First Bulgarian Empire, established in 681 after the Bulgars defeated the Byzantines. It continued to be the capital, despite its palaces being destroyed by the Byzantines in 811. Boris I established Christianity as the religion of the Bulgars in the 9th century, after which he built a massive basilica in Pliksa. It was later damaged when his son, Vladimir, attempted to reestablish paganism, but was defeated by Boris I, who moved the capital to Preslav. To move to Preslav allowed for the Bulgar Empire to develop an important regional Christian center of culture.