Mount Everest and the Galapagos Islands become accessible to students through Street View. Determining where Street View imagery is available and where it is not available is fairly easy.
For a general overview of all Street View imagery that is available worldwide, check out the map on About Street View. Scroll to about the middle of the page to find the map.
To find out if Street View imagery is available for a specific area drag the Pegman from the lower-right corner of the map onto a street. If the street turns blue, Street View imagery is available for it.
A third way to find Street View imagery is to visit Street View Collections. Street View Collections feature interesting places from around the world. It is in Street View Collections that you will find imagery for Mount Everest, the Taj Mahal, and UNESCO World Heritage Sites.
H/T to The Google Earth Blog for the inspiration for this post.