Gressholmen

Gressholmen Airport (Norwegian: Gressholmen sjøflyhavn) was a water aerodrome situated the island of Gressholmen in Oslo, Norway. It served as the main airport for Oslo from 1927 to 1939, along with Kjeller Airport. The aerodrome consisted of docks, a landing ramp, terminal building and a hangar and used a section of the Oslofjord as its runway. Being located on an island it was necessary to transport passengers by boat to the island. The airport only operated during the summer, typically from May through September. Oslo's first airport was located on the neighboring island of Lindøya, but the authorities preferred Gressholmen as a location. Although plans surfaced in 1919, funding was not ensured until 1926. Norsk Luftruter received a concession to operate the airport, ground handling and the ferry service. Deutsche Luft Hansa commenced the first service on 18 July 1927, flying from Oslo via Gothenburg and Copenhagen to Szczecin. The following year the terminus was moved to Travemünde outside Lübeck. The airport was also used by Halle & Peterson's Norway Post flights during the early 1930s and by Widerøe in 1934. Norwegian Air Lines (DNL) started domestic flights and an international service to Amsterdam in 1935. Deutsche Luft Hansa moved its flights to Kjeller from 1938 and from 1 July the following year all civilian traffic was transferred to Oslo Airport, Fornebu. Gressholmen saw a limited amount of use by the Royal Norwegian Navy Air Service, the Luftwaffe and the Royal Norwegian Air Force until it was closed in 1946. Most of the facilities, including the hangar, remain today and are used for a marina.

Heggholmen Lighthouse (Norwegian: Heggholmen fyr) is a coastal lighthouse located in the Oslofjord, in the municipality of Oslo, Norway. It was established in 1827, and automated in 1972. The lighthouse was listed as a protected site in 1998.

Lindøya is a small island located in the Oslofjord, just south of central Oslo. Administratively it belongs to the borough of Gamle Oslo. In 1920, Lindøya was the Oslo base for the pioneer Norwegian airline, Det Norske Luftfartrederi, and its seaplanes. The operation only lasted until the autumn of 1920. When regular seaplane routes were again established in 1927, the operation was moved to neighboring Gressholmen.

Bleikøya is an island in the inner part of Oslofjord, in the municipitality of Oslo. It is located between Hovedøya and Sjursøya. From the late 19th century, a sanatorium for children suffering from scrofula was located on the island.In 2008 the Bleikøya Nature Reserve was established on the northeastern part of Bleikøya, including the islet Bleikøykalven.

Langøyene is an island in Bunnefjorden in the inner part of Oslofjord, in the municipitality of Nesodden in Akershus, Norway. It is owned by the municipality of Oslo. Langøyene were originally two islands, Nordre Langøy and Søndre Langøy. The islands were bought by the municipitality of Kristiania in 1902, and the strait between the two islands has been filled with garbage deposits.

The National Internment Camp for Women in Hovedøya (Norwegian: Statens interneringsleir for kvinner, Hovedøya) was Norway's largest internment camp for women, located on the island of Hovedøya in Oslo. It was used to detain women who had been accused of having romantic or sexual liaisons with German soldiers during World War II.

The Oslo Tunnel (Norwegian: Oslotunnelen) is a 3,632-metre (2.257 mi), double-track, railway tunnel which runs between Olav Kyrres plass and Oslo Central Station (Oslo S) in Oslo, Norway. The tunnel constitutes the easternmost section of the Drammen Line and runs below the central business district of Oslo. It features the four-track Nationaltheatret Station, Norway's second-busiest railway station, where the Oslo Tunnels lies directly beneath the Common Tunnel of the Oslo Metro. At Frogner, the Elisenberg Station was built, but has never been used. The tunnel is the busiest section of railway line in Norway and serves all west-bound trains from Oslo, including many services of the Oslo Commuter Rail and the Airport Express Train. Traditionally, Oslo had two stations, the larger Oslo East Station (or Oslo Ø, located at the spot of the current Oslo S) and Oslo West Station (Oslo V), which served the Drammen Line. This caused a physical barrier between the two parts of the railway network, only connected by the Oslo Port Line which ran partly in city streets. Formal planning of a central station and a tunnel connecting the Drammen Line to Oslo Ø started in 1938, and the final plans were approved in 1968. The Oslo Tunnel opened on 1 June 1980, and made it possible to close Oslo V in 1989. Nationaltheatret saw a major upgrade in 1999, when it was expanded to four tracks, and from 2008 to 2010, the tunnel saw a major technical upgrade. There are plans to build a second tunnel to increase train capacity west of Oslo.

Hovedøya Abbey (Hovedøya kloster) was a medieval era Cistercian monastery on the island of Hovedøya in Oslofjord outside of Oslo, Norway.

Hovedøya is one of several small islands off the coast of Oslo, Norway in the Oslofjord. The island is quite small, no more than 800 metres across in any direction, the total area is 0,4 square kilometre. It is well known for its lush and green nature, with a wide variety of trees, bushes and flowers. For many, many years there was a military base on the island.

Nakholmen (also spelled Nakkholmen) is an uninhabited island in the inner part of Oslofjord, in the municipitality of Oslo. It is located west of Lindøya and southeast of Bygdøy. The island has more than 180 weekend cottages.

Tjuvholmen skulpturpark is a sculpture park in the Tjuvholmen neighborhood of Frogner borough in Oslo, Norway. It is close to Aker Brygge.

Bunnefjorden, sometimes referred to as Bunne Fjord, is a part of the Oslofjord in south eastern Norway, located east of the Nesodden peninsula. The Bunne Fjord is flanked by the municipalities of Oslo in the north east, Nordre Follo to the east, Ås to the south east, Frogn to the south west, and Nesodden to the west. The Bunne Fjord has a very long water residence time, and the water is of poor quality. The significant islands in the Bunne Fjord are Langøyene, Malmøya, Ulvøya, Ormøya, Gressholmen, and Husbergøya.