If you have any interest in dance then The Dance Museum is a must in Stockholm! It's a quite small museum, but the atmosphere is magic. The collection are very beautiful illustrating dance, drama, art and music of different continents and civilisations, and there are also often a temporary exhibition. Even if you don't want to visit the exhibition part the café is in itself worth a visit. It's cosy and you have a gorgeous view over the royal castle and Old town (Gamla stan).