This master thesis presents double basilicas on the territory of the Roman province of Dalmatia. It is about two separate structures mostly situated side by side and oriented in the East – West direction. The two basilicas are often situated parallely and rarely axially, one behind the other. It is most likely that double basilicas originate on the model of the first Cathedral in Aquileia, but in the Roman province it is believed that the main model is Salona. Double basilicas in the Roman province of Dalmatia originate from the beginning of the 5th till the end of the 6th century. Most of them were built gradually, only in the exceptionate situations the basilicas were built simultaneously. In the case of building the basilicas one after the other, the reason for constructing the new basilica can be the believers' increasing number. Double churches also had the purpose of serving miscellaneous ceremonies. The experts and the researchers (explorers) still do not have the consensus of opinion either on the reason for the genesis of double basilicas either on their function.