The Dec. 7, 1941, Japanese attack on the U.S. Pacific fleet anchored at Pearl Harbor was a devastating blow to American military might. In about two hours, 21 ships were either sunk or damaged beyong repair, 188 aircraft were destroyed and 2,403 Americans were killed.

A special floating memorial now sits above the wreck of the USS Arizona, one of eight battleships destroyed that day. It's the only part of the military base, near Honolulu, open to the public, and visiting it makes for a sobering experience. The ship, which serves as a tomb for more than 1,100 of its crewmembers killed in the attack, is still visible. The National Park Service operates the memorial. Free tours run from 7:30 a.m. to 3 p.m. every day.

One of the battleships that survived Pearl Harbor is now a floating museum. The USS Missouri, aboard which the Japanese surrendered on in Tokyo Harbor, and which later took part in the first Gulf war, is now moored alongside the Arizona memorial. Guided tours, hosted by Navy veterans, take visitors to the actual surrender site as well as sweeping views of the harbor from the Missouri's bridge. Tours run daily from 9 a.m. to 5 p.m. Admisssion costs $16 for adults and $8 for children. For more information visit the Missouri's Web site.