't Gasthuys, City museum in Aalst, Belgium

't Gasthuys occupies the former Onze-Lieve-Vrouwhospital, a red-brick complex with two connected sections. The left section has a steep pointed gable and a tall pointed-arch window above a dark wooden door; the right section has a broader pointed-arch doorway with a green recessed door and fanlight. A blue bicycle leans against the brickwork between the doors.

The building started as a hospital serving the local population across many centuries. It was later transformed and now serves as a place where the story of Aalst is preserved and shared with visitors.

The museum's name, 't Gasthuys, means guest house, and by the entrance a Gastentafel offers newspapers, magazines, books and coffee. The permanent displays cover Aalst Carnival since the Middle Ages, including float building, the princes-carnaval, the Voil Jeanet, the Aalst Gilles and the Ros Balatum. A section on Adolf Daens, made with the D.A.D.D. archive, addresses child labour and the daensisme movement.

The museum occupies the former Onze-Lieve-Vrouwhospital complex in Aalst's oldest core. The entrance is through the pointed-arch doorway in the broader right-hand brick section; a blue bicycle often leans against the wall between the two doors. The full building has been used as the Stedelijk Museum since 1959–1965 and was protected as cultural heritage in 1991.

The carnival section covers the parade floats, the princes-carnaval, the Voil Jeanet, the Aalst Gilles and the Ros Balatum, and sets the event against historical studies of popular festivity since the Middle Ages. The museum also keeps a 16th-century tapestry, old printing presses and a steam fire engine.