HDMS Indfødsretten (1786)

Middelgrundsfortet or Fort Middelgrund, known as Ungdomsøen (The Youth Island) since 2015, is a sea fort located on an artificial island in the Øresund between Copenhagen and Malmö. The fortress is constructed at a point where the seabed is 7 meters below the water surface, and at the northern meeting point of the straits Kongedybet and Hollænderdybet.

Ungdomsøen (The Youth Island) is a youth camp located on the artificial island of Middelgrundsfortet in the Øresund sound between Copenhagen and Malmö.

Middelgrunden is a shoal in the Øresund, the strait that separates Denmark from Sweden. It is the site of the Middelgrunden wind farm and the Middelgrundsfortet.

The Middelgrunden wind farm stands on the shoal Middelgrunden, between shipping lanes in the Øresund, 3.5 km outside Copenhagen, Denmark. When it was built in 2000, it was the world's largest offshore farm, with 20 turbines (2 MW Bonus each) and a capacity of 40 MW. The farm delivers about 4% of the power for Copenhagen.In 1996, the project was initiated by the Copenhagen Environment and Energy Office (CEEO) after Middelgrunden had been listed as a potential site in the Danish Action Plan for Offshore Wind. Together with the CEEO a group of local people formed the Middelgrunden Wind Turbine Cooperative and established a cooperation with Copenhagen Energy, the local electric utility. The proposed location was initially opposed by the Danish Society for Nature Conservation, but this decision was later changed. Concrete gravity base foundations were chosen as the cheapest option.This project is an example for community wind energy. It is 50% owned by the 10,000 investors in the Middelgrunden Wind Turbine Cooperative, and 50% by the municipal utility company. It is clearly visible from the capital of Denmark.

Flakfortet, meaning sand-shoal fortress, is a sea fort located on the artificially built island of Saltholmrev, in the Øresund between Copenhagen and Saltholm. The island and fort are simply known as Flakfortet; the name of the island; Saltholmrev, meaning the reef near Saltholm, is seldom used. Flakfortet was the last of three artificial islands that the Danes created to defend the entrance to Copenhagen's harbor. (The other two are Trekroner Fort (the oldest) and Middelgrundsfortet.) Flakfortet's guns covered the Hollænderdybet channel between Middelgrundsfortet and Saltholm, and the Flinterenden channel between Sweden and Saltholm. Eventually Flakfortet became more of a site for anti-aircraft weapons than for coastal artillery. Its military functions ended in 1968. Flakfortet is currently used for recreational purposes such as concerts, and the site has a restaurant and yacht moorings. During the summer, a ferry company, Spar Shipping, has five scheduled trips per day to the island, with the trip from Nyhavn taking about 40 minutes each way. There is an overnight hostel on the island too.

Prøvestenen, also known as Benzinøen, is an artificial island off the northeast coast of Amager in Copenhagen, Denmark. It is located between the Amager Hill combined incineration plant and ski slope to the north and Amager Strandpark to the south. It was created as a marine fortress to guard the entrance to Copenhagen Harbour in the second half of the 18th century and served military purposes until 1922. It now houses the city's petroleum harbor. Prøvestensbroen at the end of Prags Boulevard links it with the rest of Amager.

Trekroner Søfort (literally Three Crowns Sea Fortress) is a sea fort at the entrance to the Copenhagen harbour. From 1713 until after World War I, Trekroner Fort was part of the fortifications of Copenhagen. The original location of Trekroner Fort was a few hundred meters north of the current one. In 1713, three old ships of the line were sunk to form the basis for a battery. One of the ships was called Trekroner, and she gave her name to the fort. Construction of the current fort began in 1787. The fort was an important part of the Danish line of defense during the Battle of Copenhagen in 1801. The fort also was engaged during the British attack on Copenhagen in 1807. From 1818 to 1828 and in 1860, the fort was strongly enhanced, but its military significance diminished after the First World War. In 1934 it was sold to the Copenhagen harbour services. During the German occupation of Denmark the Germans used the fortress as a barracks. After the war it was used for a few years as a prison for German officers and the former German ambassador to Denmark. Afterwards, it fell vacant until 1984, when it was opened to the public. Trekroner Fort is one of three artificial islands that were created to defend the entrance to Copenhagen's harbor. (The other two are Middelgrundsfortet and Flakfortet.)

The Battle of Copenhagen of 1801 (Danish: Slaget på Reden, meaning "the battle of the roadstead [of Copenhagen Harbour]"), also known as the First Battle of Copenhagen to distinguish it from the Second Battle of Copenhagen in 1807, was a naval battle in which a British fleet fought and defeated a smaller force of the Dano-Norwegian Navy anchored near Copenhagen on 2 April 1801. The battle came about over British fears that the powerful Danish fleet would ally with France, and a breakdown in diplomatic communications on both sides. As the British ships entered the harbour of the Danish Navy, several of its ships took up station at the harbour's roadstead, forming a blockade. The Danish fleet defended the capital with these ships and bastions on both sides of the harbour inlet. It was the second attempt by the British to try to prevent a Franco-Danish alliance, as the British had already entered Øresund with a fleet in August 1800, in order to persuade Denmark not to ally with France. The Danes agreed to the British terms upon hearing news of the assassination of Tsar Paul I of Russia, as his death meant the end of the Russian-led League of Armed Neutrality of which Denmark was a member.

B&W Hallerne (English: The B&W Halls) is a former industrial complex located on the island of Refshaleøen in Copenhagen, Denmark. Built in the early 1960s by Burmeister & Wain, the complex consists of two large halls which were used to build ships until 1996. Currently, the facilities are used for culture and entertainment activities.On 2 September 2013, Danish public broadcaster DR announced that it had chosen B&W Hallerne as the host venue for the Eurovision Song Contest 2014. The contest was held at the Section Hall 2, which was converted into a music venue with a capacity for 11,000 spectators. The surrounding buildings and areas were transformed into "Eurovision Island" which was used for additional services related to the contest.

Refshaleøen is a former industrial site in the harbor of Copenhagen, Denmark originally on a separate island but now annexed to the larger island of Amager. For more than a hundred years, it was home to the shipyard Burmeister & Wain which closed in 1996.

Copenhagen Suborbitals is a crowd-funded, open-source human space program. It has flown five home-built rockets and two mock-up space capsules since 2008. The organization successfully launched its Nexø II rocket in the summer of 2018. Its stated goal is to have one of its members reach space (above 100 km) on a sub-orbital spaceflight. The organization was founded by Kristian von Bengtson and Peter Madsen.The program's 55 members work on it during their free time and elect a chairman and board members at their annual general assemblies. As of 2019, the chairman is Carsten Olsen.

Nordhavnen, or Nordhavn, is a harbour area at the coast of the Øresund, founded at the end of the 19th century in Copenhagen, Denmark. It covers an area of more than 2 km². Today, most of Copenhagen Harbour's traditional activities are situated in Nordhavn, including ferry berths, a container terminal, marina, and industrial companies. The S-train station Nordhavn station is located at Nordhavnen close to the city district Østerbro.