Derby Castle Depôt is the main location of workshops and running sheds of the Manx Electric Railway on the Isle of Man and lies at the northerly end of the promenade at Douglas; it takes its name from the adjoining site which was once home to the Earls of Derby, rulers of the island, and later extended to form an entertainment complex of the same name before being demolished and replaced by the ill-fated Summerland complex in 1968.