Although Columbus Day is often shrouded in controversy, it certainly represents a watershed event in the history of civilization. Thus, Happy Columbus Day!
Lat year I wrote twice about this holiday. For an interesting science fiction take on this seminal interaction between the New World and the Old see "Fixing the New World domination by Eurasian originating civilizations through recourse to science fiction". For actual academic analysis of what the New World was like just before Columbus got there, see "The day before Columbus Day".
(Stained Glass Window design from the Library of Congress)