[2] Formerly the property of the Navy, today it houses the National Naval Museum (Marinmuseum), one of Sweden's oldest founded in 1752, the Hyper Island educational complex, and several other historic buildings.

[3] The unusual Slup- och barkass- skjulet (Sloop and Longboat Shed) is noted for its remarkable roof while buildings on Laboratorieholmen once served as an isolation hospital when the town was struck with disease.

[4][5] Comprehensive restoration and renovation work has been undertaken since the 1990s, providing a variety of interesting sights for tourists as well as residential accommodation for senior citizens.

[1] In 1683, under King Karl XI, fortification plans were drawn up, providing workshops and stores for shipbuilding and provisioning.

In 1782, Fredric Henric af Chapman was charged by King Gustav III to modernize shipbuilding methods in order to create a large new fleet.

Over the years, there have been bakers, distillers, brewers, butchers, a textiles factory and, as both water and provisions were generally stored in barrels, a coopers’ workshop on the island.

There are military buildings from the early 18th century, some designed by the commander in chief of the naval base, Carl August Ehrensvärd, who had taken an interest in Greek and Roman architecture.

As a result of an architectural competition, preservation work on 17 buildings was undertaken in the 1990s adhering to the general prínciple of "a quality conscious conversion of an historic environment".

Development of residential facilities has provided over 150 apartments on the island, all reserved for rental or purchase by senior citizens.

The foundations of the museum were laid in 1752 when King Adolf Frederick established the Navy's model chamber with artifacts representing the various vessels.

It includes an underwater observation tunnel, a naval warfare gallery, a full-scale reconstruction of the gun-deck of the Dristigheten and an exhibition of ship's figureheads, most of which were carved by the 18th-century sculptor Johan Törnström.

Built in 1821–1826 in the Neoclassical style, the well-preserved stone building with a deeply pitched roof is probably the oldest guardhouse in Sweden.

[16] One of Karlskrona's oldest buildings, the Bageribostället (Bakery Living Quarters), was built in the late 1600s and was originally an artillery workshop.

After the artillery works were moved to Trossö Island in the 18th century, the building was used to accommodate crews from the bakery ships.

[17] Kronohäkte (the Crown Prison) built in 1910–1911 was designed by F. Bothén according to the Philadelphia Model approach with open floors to supervision easier.

Today it offers teaching facilities for the Hyper Island Business Management and Digital Media school which was founded in 1996 (see below).

[18] The disinfection building, hospital pavilion and fumigation shed are located on Laboratorieholmen which was once a separate island used as the site of a cannon foundry.

After the 1788–1790 campaign against Russia, the returning fleet brought ship's fever, a form of typhus, to the city causing some 10,000 to lose their lives.

With support from the Swedish Ministry of Education, the school offers vocational courses in Digital Media, Management and Leadership based on "learn by doing" principles.