The capital and administrative center of Bornholm is Rønne, which also has the island's airfield and its principal harbor. The harbor is separated into ferry, fishing and yachting basins. There is also a yacht harbor for pleasure boats farther north at the beginning of the northern coastal road (Nordre Kystvej).
In the south of Rønne stands the castle, built about 1650, with its massive round tower. It has been converted into a defense museum where weapons, maps and models of fortifications are on display.
The interesting Bornholm Museum at Skt.-Mortens-Gade 29 possesses a collection covering seafaring history and the natural history (granite, limestone, coal and kaolin specimens) of Rønne and Bornholm; there is also a history of art department with works by Bornholm painters as well as drawings and examples of the decorative arts.
The museum houses several interesting artefacts, including wartime memorials, old clocks, and items of gold.The Bornholm museum also offers activities for children.
Many old houses survive in the streets around the Rønne church, including the half-timbered Erichsens Gård (1807) in Lakesgade and the main police station (1745) in Søndergade.
On a hill above the harbor of Rønne in the oldest part of the town stands St Nicholas' Church, originally 14th C. but largely rebuilt in 1918. Note the font from the island of Gotland.