Stockholm is one of the major museum cities of the world and is the proud home to over one hundred museums in total.
All museums in Stockholm follow the general international museum standard and are closed on Mondays.
It is worth considering purchasing a Stockholm Card from the tourist office for SEK 270 that will get you free entry into museums as well as a number of transport, event an activity discounts.
Below is a list of museums in the city to get you going;

Aquaria Water Museum 
Falkenbergsgatan 2,
115 21 Stockholm,
Tel: +46 8 660 90 89 

Swedish Museum of Arcitecture 
Skeppsholmen,
111 49 Stockholm,
Tel: +46 8 587 270 14 

The Museum of Dance 
Gustav Adolfs Torg 22-24,
111 52 Stockholm,
Tel: +46 8 441 76 50 

Museum of National Antiquities 
Narvavägen 13-17,
114 60 Stockholm,
Tel: +46 8 519 556 00 

Toy Museum 
Tegelviksgatan 22,
116 41 Stockholm,
Tel: +46 8 640 44 92 

Museum of Mediterranean and Near Eastern Antiqities 
Fredsgatan 2,
103 21 Stockholm,
Tel: +46 8 5195 50 50 

Modern Museum 
Skeppsholmen,
103 27 Stockholm,
Tel: +46 8 519 552 00 

Museum de Vries 
Drottningholm,
178 02 Drottningholm,
Tel: +46 8 402 62 80

The National Museum of Fine Arts 
Södra Blasieholmshamnen,
103 24 Stockholm,
Tel: +46 8 519 543 00 

The Swedish Museum of Natural History 
Frescativägen 40,
104 05 Stockholm,
Tel: +46 8 519 540 00 

National Maritime Museum 
Djurgårdsbrunnsvägen 24,
102 52 Stockholm,
Tel: +46 8 519 549 00 

Skansen Open-Air Museum 
Djurgårdsslätten 49,
115 93 Stockholm,
Tel: +46 8 442 80 00 

Skansen's Aquarium 
Djurgårdsslätten 49,
115 93 Stockholm,
Tel: +46 8 442 80 39 

City Museum of Stockholm 
Ryssgården,
104 65 Stockholm,
Tel: +46 8 508 316 00 

Museum of Technology 
Museivägen 7,
115 93 Stockholm,
Tel: +46 8 450 56 00 

The Vasa Museum 
Galärvarvsvägen 14,
102 52 Stockholm,
Tel: +46 8 519 548 00