Malbork
Malbork is a gothic castle. Its volume is 250 000 m³. Teutonic Knights were building it from 1274 to 1457. Malbork was the capital of Teutonic Knights from 1309 to 1457. It was written down to the UNESCO list in December 1997. There wiil be a special performance in the castle called „With cross and sword”. It will be from 15 April 2010 to 15 September 2010. Today in Malbork there is a museum with a set of amber and thematic exhibitions showing life in former centuries. UFO is hiding in vaults of the castle - some people say that. The woman was bricked at one time in the tower called the „Maślankowa” tower.
http://en.wikipedia.org/wiki/Malbork

The Międzyrzecz Fortification Region
It is a fortified military defence line in Western Poland, between the Odra river and Warta river. It was built between 1934-1938. It was the most technologically advanced fortification system of Nazi Germany, and remains one of the largest and the most interesting systems of this type in the world today. It is also the largest European underground bats refuge, giving shelter to about 32,000 bats of 12 species in the wintertime. In other seasons tourists can tour bunkers.
http://www.youtube.com/watch?v=hs4ueaxXrsk