ON THIS DAY IN HISTORY: Today in 1513, Spanish explorer Ponce de Leon saw Florida, but thought it was an island, so he kept sailing.

ON THIS DAY IN HISTORY: Today in 1889, designer Gustave Eiffel presided over a ceremony in Paris to open the now-iconic Eiffel Tower.

ON THIS DAY IN HISTORY: Today in 1981, drifter John Hinckley Jr. tried to assassinate President Reagan outside a Washington, DC hotel.

ON THIS DAY IN HISTORY: Today in 1973, the last U.S, combat troops withdrew from Vietnam, at the end of a contentious eight-year war.

ON THIS DAY IN HISTORY: Today in 1979, a nuclear reactor dangerously overheated at the Three Mile Island power plant in Pennsylvania.

ON THIS DAY IN HISTORY: today in 1953, Jonas Salk announced that he had discovered a vaccine for poliomyelitis, a main cause of polio.

Tragedy...

ON THIS DAY IN HISTORY: Today in 1911, a fire at the Triangle Shirtwaist factory in NY killed 146 due to hazardous working conditions.