Complex sentence: The seat of the Patriarchate was the new Bulgarian capital of Preslav, although the Patriarch is likely to have resided in the town of Drastar (Silistra), an old Christian centre famous for its martyrs and Christian traditions.
Split into simpler sentences: The seat of the Patriarchate was the new Bulgarian capital of Preslav. The Patriarch was likely to have resided in the town of Drastar (Silistra), an old Christian centre famous for its martyrs and Christian traditions.