The Victoria and Albert Museum is not only the world's largest museum of decorative arts and design, but is always on my to do list when I head to London.
Not that I have counted, but it boasts 145 galleries and with 12.5 acres of museum space attracting tourists who flock to see the massive collections of post-classical sculptures and South Asian art. The good thing about that is they never make it to the harder to find collection of photography. It is always changing and a great source of inspiration.
The fashion and textile gallery is always worth a look. Spent a while sketching a dress designed but the late Alexander McQueen, that took inspiration from a butterfly. They also have a collection on designer menswear, including now vintage suits from Paul Smith, Yves Saint Laurent and an original and eye catching Tommy Nutter! (Now he is one designer I would have liked to meet). Due to the variety of collection, the newly designed garden space, the grand eating space along with the V&A being a great source of inspiration, if you have yet to visit ... GO!!!