On this day in 2005 London was attacked by Al Qaida with 3 simultaneous attacks during rush hour, and an attack on a bus about an hour later, killing 56 people and injuring 700. The attacks were planned for the subway system and shut down London transit for days. They took place as the leaders of the world were meeting in Scotland for the G8 summit.
On this day in 1930 construction began on the Hoover Dam. This immense undertaking was done to provide power and water to people in the desert southwest. The name of the dam has changed from Hoover to Boulder a few times, but the hatred for president Hoover seems to have subsided, so I think it'll stay Hoover dam for the time being.
On this day in 1980 Led Zeppelin performed with their original four members for the last time. John Bonham died later that year. They have since performed a few times with other drummers, but have yet to record any new material. A rumored tour with John's son Jason was in the works, but Robert Plant has been busy with his own material.
On this day in 1865 the US federal government executed its first woman when Mary Surratt is hanged for conspiracy to murder president Lincoln. She owned the boarding house where John Wilkes Booth and his co-conspirators planned their attacks on the US government.