Victoria and Albert Museum, London
Museum for Textiles
Well of COURSE I'm including a couple of string museums!
Museum of National Antiquities, Sweden
Definitely a find: pictures and information on many of the Museum's artifacts, and a virtual tour.
The Medieval Centre
Centre for Historical Technology.
Check out the trebuchet! Also good firearms information.
Rosslyn Chapel, Scotland
Photographs of stone carvings ornamenting this 15th century building.