Short answers, pulled from the story.
Checkpoint Charlie was the Western Bloc's most prominent crossing point between East Berlin and West Berlin during the Cold War. It sat at the junction of Friedrichstrasse with Zimmerstrasse and Mauerstrasse in the Friedrichstadt district of Berlin, and was the only crossing designated for Allied military personnel, foreign diplomats, and tourists.
East Germany built the Berlin Wall in August 1961 to halt mass emigration. Between 1949 and 1961, more than two and a half million East Germans had fled to the West, including large numbers of engineers, physicians, teachers, and other skilled workers whose loss was damaging the country's economic and political stability.
On the 27th of October 1961, ten Soviet tanks and ten American tanks faced each other one hundred yards apart at Checkpoint Charlie, after a dispute over East German guards checking the documents of a US diplomat named Allan Lightner. The stand-off ended peacefully on the 28th of October after back-channel talks between US Attorney General Robert F. Kennedy and Soviet intelligence officer Georgi Bolshakov.
Peter Fechter was a young East German who was shot in the pelvis by East German border guards on the 17th of August 1962 while attempting to escape across the Berlin Wall near Checkpoint Charlie. He fell in barbed wire just metres inside the Soviet sector and bled to death over the course of more than an hour, in full view of the world's press, as neither side was able or willing to reach him.
The checkpoint booth was removed on the 22nd of June 1990, after the Berlin Wall opened in November 1989, and the crossing remained officially open for foreigners and diplomats until German reunification in October 1990. Today the site is a major tourist attraction featuring a replica guard house, an open-air exhibition opened in summer 2006, and the nearby Mauermuseum, which drew 850,000 visitors in 2007.
The name Charlie comes from the letter C in the NATO phonetic alphabet. It followed the same naming logic as other Allied checkpoints on the Autobahn from the West: Checkpoint Alpha at Helmstedt and Checkpoint Bravo at Dreilinden.