Wellington Arch London, also known as Constitution Arch was originally conceived as the gateway to Buckingham Palace but ended up being erected at Hyde Park Corner. You can visit the Wellington Rooms and their great advantage point to see the surrounding area and the Horse Guards pass through the arch every day.
In September of 1940, Witold Pilecki (May 13, 1901 – May 25, 1948) was a Polish Resistance solider who wanted to know the truth about Auschwitz. He volunteered to infiltrate the nazi death camp, spending the next 2.5 years as a prisoner. On his escape, Pilecki smuggled details about the nazi methods of execution and interrogation and eventually authored the first WWII intelligence report on the concentration camp.