You can add these map layers to ArcGIS Explorer.
U.S. Topographic Maps
Land-cover imagery for the world and detailed topographic maps for the United States at multiple scales
World Historical Map 1812
"The World on Mercator's Projection" from the David Rumsey Historical Map Collection
World Street Map
Presents highway-level data for the world and street-level data and more for North America and Europe
World Transportation
Presents transportation data, including highways, roads, railroads, and airports, for the world
