What was the true nature of the Lewis and Clark expedition--and what does it have to do with Mount Rushmore?

The Battle of the Plains of Abraham might just have been the moment when Britain was vaulted into global superpower status--a historical first?

Cahokia may have once been the largest city in North America (north of Mexico), with tens of thousands of inhabitants and massive pyramids...right outside of modern-day Saint Louis.

Who discovered America for the Eastern Hemisphere? Everything changed after Columbus, true, but were there other non-natives before him? How does the settlement of Iceland play into this history--and did the Vikings influence Columbus himself?