長崎 (Nagasaki) is most famous for the explosion of one of the two atomic bombs in 1945. I went there to attend the International Conference on Embedded and Ubiquitous Computing (aka EUC2005). Before leaving I had the opportunity to visit the main touristic places of the city, including the atomic bomb museum.
If you want more information about the area, please check the guide page for 長崎 (Nagasaki).