Colosseum, Industrial architecture at Alleestrasse, Bochum, Germany.

The Colosseum in Bochum is a monumental supporting wall built from 2.8 million bricks reaching 16 meters high, marking the southern boundary of Westpark. The structure once formed the foundation of a large industrial facility and remains today as a striking remnant of brick and steel.

The structure was built in 1911 as part of the Martin-Stahlwerk steelworks and served the heavy industry until 1983. After production ceased, most buildings were demolished, but this wall remained standing as a witness to that era.

Steel sculptures by local artist Friedrich Gräsel display painted industrial pipes integrated into the arched facade. This art installation makes the industrial past of the site visible and tangible to visitors.

The square in front of the wall reopened in early March 2010 after renovation and is freely accessible. The site lies at the entrance to the former Krupp grounds on Alleestraße and forms the southern edge of Westpark. The arched facade with Gräsel's seven steel sculptures faces the square, so the wall is best viewed on foot from there.

The lower part of the wall retains narrow crawl passages that served as substitute air-raid shelters for Krupp steelworkers in World War II, linked to a wide underground protection network. Visitors can still see the washbasins and tubs of the former changing rooms above.