- British Museum, London
- Guggenheim Museum, New York
- National Gallery of Art, Washington, D.C.
- Musée d’Orsay, Paris
- National Museum of Modern and Contemporary Art, Seoul
- Pergamon Museum, Berlin
- Rijksmuseum, Amsterdam
- Van Gogh Museum, Amsterdam
- The J. Paul Getty Museum, Los Angeles
- Uffizi Gallery, Florence
- MASP, São Paulo
- National Museum of Anthropology, Mexico City
A few years ago Mental Floss had a similar article titled 12 World-Class Museums You Can Visit Online. There isn't much overlap between the two lists.
- The Louvre
- Solomon R. Guggenheim Museum
- National Gallery of Art
- British Museum
- Smithsonian National Museum of Natural History
- The Metropolitan Museum of Art
- Dalí Theatre-Museum
- NASA Space Center
- Vatican Museums
- National Women's History Museum
- National Museum of the United States Air Force
- Google Art Project
Last for the Museum virtual tours is the massive list from Lifehacker: You Can Virtually Tour These 500+ Museums and Galleries From Your Couch.
Plenty of sites are providing lists of things to do and helpful links, such as Open Culture's Use Your Time in Isolation to Learn Everything You’ve Always Wanted To: Free Online Courses, Audio Books, eBooks, Movies, Coloring Books & More. If you have to be stuck inside, it's amazing how much is so easily available.