There was probably no more visible symbol of the Marianas than the Palacio, the residence and office of the governor and the seat of his authority. The residence, like the colony itself, had beginnings in the barracks of the military compound before it took on distinctive features and eventually achieved prominence in the capital of Agaña.
The Jesuit mission established a foothold near the beach on an island-like area formed by two outflows of the Agaña River. Gradually, the Spanish compound moved inland until it reached the hillside, though not before a second Spanish settlement at Umatac gained prominence as the principal port in the Mariana Islands. For a considerable time two Palacios, or residences for the governor, existed on the island of Guam.
The story of the Agaña Palacio is more than the history of a public building, insofar as this can be reconstructed from the sources. To some extent the vicissitudes of the Palacio reflect the shift in Spanish policy in the colony, and the events that helped shape this policy over the more than two centuries of colonial rule in the islands. - from Amzon