The Qasba of Chefchaouen is the oldest part of the city, largely built in the 15th and 16th centuries. However, the northeast tower that today houses the museum, may have been added as late as the 19th century.
SOURCES:
Boujibar, Naïma El-Khatib. "Chefchaouen." In
Andalusian Morocco: A Discovery in Living Art. Vienna: Museum With No Frontiers, 2002.
Lakhdar, Kamal, and Laurence Nunny. "Discover Islamic Art – Virtual
Museum." Discover Islamic Art – Virtual Museum. Accessed December 10,
2014.
http://www.discoverislamicart.org/database_item.php?id=monument;ISL;ma;Mon01;30;en.
Roca, Juan Ramón.
Tangier and Its Surroundings, Assilah and Chefchaouen an Illustrated Guide. Alicante (C/ San Carlos, 93, 03013 Alicante): J.R. Roca, 2011.