Heggholmen Lighthouse

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.

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.

Gressholmen is an islet located in the Oslofjord, just south of central Oslo. Administratively it belongs to the borough of Gamle Oslo. Gressholmen airport was for the years 1927 through 1939 the location of the main airport for Oslo, until the construction of Fornebu airport. The airport was only for seaplanes. The ramp with rail tracks and the hangar are reused for boat storage and maintenance. There is railway point with the big track gauge. The island is easily accessible from Oslo with the local ferries. The access point is on the North side. A big part of the island is a nature reserve.

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.

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.

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.

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.

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

The 1943 Filipstad explosion was a fire in an ammunition store at Filipstad in Oslo on Sunday, 19 December 1943, during the occupation of Norway by Nazi Germany. The fire started during the unloading of ammunition from the transport ship Selma. The estimated amount of exploded ammunition varies from 800 to 1,200 tons. A large number of shells and grenades were tossed into the air and spread over the city. There were around 40 Norwegian casualties and around 75 Germans were killed, and 400 wounded. About 400 buildings were severely damaged.

Filipstad is a neighborhood in the Frogner borough in Oslo, Norway. It serves both as a major container port and ferry terminal for the city. The Oslo-Kiel ferry docks by the Hjortneskaia at Filipstad.

The Norwegian Maritime Museum (Norwegian: Norsk Maritimt Museum) is located at Bygdøynesveien on the Bygdøy peninsula, on the western side of Oslo, Norway. The Norwegian Maritime Museum is situated near several other museums, including the Fram Museum; the Kon-Tiki Museum; the Norwegian Museum of Cultural History; and the Viking Ship Museum. The Norwegian Maritime Museum is operated in conjunction with Norwegian Folk Museum.