The Auberge de Castille was the central administrative headquarters of the Knights from the Iberian Peninsula (especially those from Castille and Portugal). It was built in the 1740s to replace an earlier auberge erected in 1574. During British rule, it became a residence for military officers. A large aerial was installed on the roof in the 1880s to communicate with the Mediterranean Fleet in the harbour (the aerial was removed after the end of the Second World War). Today, the Auberge de Castille serves as the Office of the Prime Minister of Malta.