Piscine du Mosq, also known as the former Amicale Solvay, is located in Couillet (Charleroi). It is a striking brick building with a flat roof, built between 1937 and 1939 by the architect Eléazar Cozac. The building houses a swimming pool, a theater, and a restaurant. Two identical versions of this building were built. The  second is located in Jemeppe-sur-Sambre.

The striking facade is hollowed out in the middle by a large semicircle, which contains the hall and the monumental staircase, illuminated by a circular glass roof.

The building was constructed to provide Solvay employees with recreational facilities. By the early 1990s, the costs of the aging building no longer outweighed the revenue. The most expensive part of the recreation area, the basement swimming pool, was closed in 1998. The theater and restaurant remained in use until 2004, but then were also permanently closed.