Euromast is an observation tower in Rotterdam, Netherlands, designed by Hugh Maaskant constructed between 1958 and 1960. It was specially built for the 1960 Floriade, and is a listed monument since 2010.[1] The tower is a concrete structure with an internal diameter of Шаблон:Convert and a wall thickness of Шаблон:Convert.[2] For stability it is built on a concrete block of Шаблон:Convert so that the centre of gravity is below ground. It has a "crow's nest" observation platform Шаблон:Convert above ground and a restaurant. Originally Шаблон:Convert in height it was the tallest building in Rotterdam. It lost this position to the high-rise of Erasmus MC (Шаблон:Convert)[3] which was completed in 1968, but regained it when the Space Tower was added to the top of the building in 1970, giving an additional Шаблон:Convert. Euromast was the highest building of the Netherlands,[4] but was surpassed by De Zalmhaven, also in Rotterdam, in 2021. It is also a member of the World Federation of Great Towers. In 2008, 2009 and 2019, the tower hosted an extreme sports event which featured BASE jumping. A new event was expected in September 2022.