The IV District, also known as Martti (Finnish; Martins in Swedish), is one of the central districts of Turku, Finland. It is located on the east side of the river Aura, between Tervahovinkatu in the west and Betaniankatu and Martinkatu in the east. The district is one of the smallest in Turku, and is centred on the Martinkirkko church, named after the reformer Martin Luther (Martti Luther in Finnish).