Possibly the last aircraft of it's kind in the world was found off the coast of Kent last year and has been positively identified as a Dornier Do 17. The RAF is pretty sure which plane it is and of the crew of four that crashed the plane, 2 were killed and 2 were taken prisoner. The RAF Museum at Hendon is trying to raise funds to recover the aircraft and put the remains on display. There are no plans to restore the aircraft in order to keep it's originality intact. BBC story and video is here.
The Dornier 17, nicknamed the Flying Pencil because of it's unique slim fuselage, took part in the Spanish Civil War and the Battle of Britain, but by the end of 1941 it was outclassed by newer types. It was somewhat under powered as the engines it was designed for were needed for fighters, and the majority of the planes ended up with increased bombloads and lesser engines. However they handled fine at low altitudes and were popular with crews. When their use as a bomber was superseded by other aircraft they were tried out in a night fighter role, but didn't do particularly well and were removed from front line duty by mid-1942.
This video shows Do 17's used by Finnish Air Force in WW2
Found this cool picture of an 1860's era Armstrong muzzle loading gun in the U.S. National Archives photostream on Flickr. The picture was taken in Annapolis, Maryland in 1866 by Matthew Brady of all people, and is described as being in a battery. Where is this gun now, I wonder. It looks to be about a 150 pounder, a big boy, and looks brand new. There is a similiar gun at West Point that was one captured from the Confederates at Fort Fisher in 1865, a battle also known as the biggest U. S. amphibious operation before Normandy. The gun fired an exotic elongated shell with copper studs that engaged the rifling for spin, and along with this had Armstrong devised "shunt rifling". This in effect made it easy to load (which is not normally easy on a muzzle loading rifled cannon, and when fired "shunted" the shell to the shallow grooves, which made it very accurate. Also using built up coil construction this made the gun one of the most advanced guns of it's day. The Fort Fisher gun wasn't fired much in anger, due to a small number of British shells for the gun. The Confederates tried to reproduce them but didn't have much luck. The fort had about a dozen shells in all. Fort Fisher is also trying to get it's West Point gun back according to their website. I haven't found out yet what happened to the Annapolis gun, but I'm still looking.
Update:7/9/11 According to the Historical Marker Database, this gun was melted down during WW2.