Seaplane Harbour Hangars (Lennusadam)

The Seaplane Harbour hangars (Lennusadam) at Vesilennuki 6 in the Kalamaja district of Tallinn were built in 1916 to 1917 as part of Peter the Great's Naval Fortress, a Russian Empire coastal defence system planned before the First World War. They were designed as a base for seaplanes, and their construction is of international technical importance. The hangars use thin reinforced-concrete shell roofs, a pioneering structural system for the time, with very thin concrete spanning a wide open interior. The builders used innovative formwork to create a row of connected shell vaults that rise from the water's edge. After the Russian Revolution the base passed to the newly independent Estonian forces, and was used in the interwar period and afterwards by the Soviet Navy, who stored equipment there. The buildings fell into disrepair after the Soviet withdrawal in 1994 and were declared a protected industrial monument. A major restoration and conversion project was carried out in the 2000s and 2010s, led by the architecture firm KOKO, which reinforced the concrete, restored the roof shells and added glazing, re-opening the site in 2012 as the Estonian Maritime Museum. The conversion preserved the large open interior, so that exhibits such as the submarine Lembit and a historical seaplane are displayed under the vaults, and the concrete structure itself is part of the exhibition. Visitors can see the harbour ramps where aircraft once entered the water, and the historic shell roofs from the gallery. The building is a key landmark of early 20th-century engineering in northern Europe and a rare surviving example of a pre-1920 seaplane base. It stands near the Patarei sea fortress and the Kalamaja waterfront, within walking distance of the Old Town.