Mushroom, Transportation building in Moricz Zsigmond Square, Hungary.

The Mushroom is a ring-shaped building on the south-eastern side of Móricz Zsigmond Square in Budapest, built in 1942 to the plans of József Schall. Its circular form follows the loop of tram tracks laid around it, and a fountain stands in the middle of the ring, with decorations made by László Szomor. Inside were a waiting room, staff quarters, shops and an electrical converter.

Built in 1942 to designs by József Schall on what was then Horthy Miklós tér, the ring-shaped building enclosed a loop where HÉV trains from Budafok-Nagytétény and Budafok-Budaörs-Törökbálint reversed. It housed a waiting room, staff quarters, shops and a power converter. HÉV services were replaced by trams in 1963, and lines 41 and 43 terminated here until 1972. The building was listed as an industrial monument in the early 2000s and restored by May 2014.

The structure sits at Moricz Zsigmond Square, named after a Hungarian writer, and serves as a central gathering spot for District XI residents. People use this area daily as a passage and meeting place between different transit options.

The building connects multiple tram lines and metro stations, functioning as a central transfer point in southern Budapest. The open structure makes it easy to navigate between the different transit lines and platforms.

The building's original ring shape was determined by tram tracks that looped around its perimeter, creating its distinctive circular form. This engineering solution demonstrates how architecture adapted to the transit needs of its era.