The Cathedral of the Assumption (Nagyboldogasszony Főszékesegyház) is Kalocsa's defining building and one of Hungary's finest baroque churches. The present structure was built between 1735 and 1754 under Archbishop Imre Esterházy, replacing an earlier church destroyed in the Ottoman period. Its pale-yellow facade and twin towers have dominated the town's skyline for nearly three centuries.
The interior is richly decorated, with frescoes by Franz Anton Maulbertsch and elaborate marble altars. The treasury holds vestments and ecclesiastical objects spanning many centuries, including items from the medieval archdiocese. The adjacent Archbishop's Palace, connected to the cathedral complex, houses the famous archdiocesan library. Together they form one of the most intact historic ecclesiastical ensembles in Hungary.