Locks and Keys Throughout the Ages

The Medieval Household: Daily Living c.1150-c.1450

''Padlocks'' in Serce Limani: An Eleventh-Century Shipwreck Vol. 1, The Ship and Its Anchorage, Crew, and Passengers

See also Guidelines on the X-radiography of archaeological metalwork, which features a cover photo of a post-medieval padlock and an interior photo of a barrel lock. More links here, and an excellent bibliography on the subject, too.

Many more padlocks can be found at the Portable Antiquities Scheme Finds Database. Some websites selling antique (pre-17th century) locks, for additional reference: Fischer-Antics, Gaukler Medieval Wares.