Those with an interest in World War II history should make a beeline here. This small but fascinating museum contains exhibits recounting the events in the Pacific, with a particular focus on the activities of the U.S. Marine Corps. In fact, the museum was established by a former U.S. Marine and Vietnam War veteran, the late John Gerber. It has excellent displays of both American and Japanese relics, including uniforms, weaponry, equipment, and vehicles. The museum is operated by a private nonprofit organization and is separate from the U.S. National Park Service-run War in the Pacific National Park, but a visit to both is recommended to get the full story. The aforementioned national park is actually several distinct historical sites across the island, so to visit these you'll need a car (or to book a tour).
Hwy. 6, Agana, 96932, Guam