Due to the large US Naval presence, Guam is cosmopolitan and energetic. Hagåtña, the capital, has many historic buildings dating from the Spanish period. Tumon Bay, just up the coast from Hagåtña, is the main tourist centre.

Guam is the largest and most southerly island of the Marianas Islands, which were occupied by the Chamorro Indians from 1500 BC. It was claimed by the Spanish in 1565 and ruled by Madrid until the Spanish-American War of 1898.

The Spanish governor was unaware of the war and, when a US frigate entered Hagåtña harbour with guns blazing, he apologised to the captain for not having a reciprocal salute ready. He surrendered the island the next day. US rule was interrupted by the Japanese invasion of 1941, to be reinstated after fierce fighting three years later. The island has been an important US strategic base since then.