The capital of Guam is situated at the mouth of the Agana River and 5 miles north of the Apra Harbor, Agana's port of entry and the island's chief port. Developed by Spain in the 16th Century, Agana serves as the administrative center of Spain's Pacific island holdings. When Guam was ceded to the United States at the end of the Spanish-American War, a naval base was established in Apra Harbor. Japan briefly held Agana during World War II before its recapture by the United States in 1944.

Agana has several historical sites of note, including the Dulce Nombre de Maria, or Agana Cathedral, built by the Spanish in 1699 and the Latte Stone Park, whose pillars date from over two thousand years ago and are believed to be house pillars used by the ancient Chamorro people in the construction of homes.