The mushroom is a water tower in the Norr district of Örebro . The mushroom was designed by architects Sung Lindström and Paul Kühl in AB Vattenbyggnadsbyrån (VBB) in Stockholm. The water tower is 58 metres high and holds 9 million litres of water. It was opened in May 1958 and then replaced the South Water Tower and the North Water Tower. A café and a conference hall are located on the first floor of the tower. The Mushroom had about 100,000 visitors per year before the online cage (see below).
The Mushroom was built in 1956-1958. The project was very much in its day. The site goes down 10 meters underground and another 20 meters below are the main reinforcements. They started by pouring a water tank ("hat") into a wooden form on the ground. It weighs 3200 tons. Then it was gradually raised by 32 hydraulic jacks (see image below), resulting in a "leg" cast from below. The growth took place at a speed of 58 cm per day.
The reservoir is 45.5 metres in diameter and the lower part of the tower on the ground surface is 10.5 metres in diameter. There are two elevators to the balcony. There is also an emergency staircase consisting of 300 steps.