I recently stumbled across this and wanted to share for those who may not know and are interested in some of the museums in NYC. It may help you decide if you want to go there in person or not. Google Street View actually takes you inside some places. I saw this first looking at the location of The Cloisters. It also works with the Metropolitan Museum of Art and Museum of Modern Art.
To access this, zoom in to where you can see the building on the map; click the yellow person icon on the left and drag over the building. If it is available, you will see blue lines. Just click a spot and navigate through just like the regular street view. Have fun!