The site of the discovery of San Francisco Bay consists of the point at which the Portolá Expedition crossed over Sweeney Ridge in 1769, and for the first time, came to view one of the world's largest sheltered anchorages.

From the top of Sweeney Ridge one can see not only inland to the Bay, but north along the ocean coast as far as Point Reyes.

Total acreage is approximately 18.15. No structures are on the site or in the immediate vicinity.

Captain Caspar de Portolá and his party of sixty men (with a caravan of two hundred horses and mules) had come from San Diego in search of Monterey Bay, but from their overland approach, they had failed to recognize it. They had come north, climbed over San Pedro Mountain and had made camp in Pedro Valley, now in the city of Pacifica. Though already within today's Bay Area, they were still unaware of the Bay's existence.

The following morning, November 1, 1769, Sergeant Ortega and a squad of scouts began a three-day reconnoitering tour. They saw San Francisco Bay on his first day of scouting.

When Ortega returned to camp on November 3, Portolá's next move was an attempt to go around this new found "estuary" to examine the vicinity of Point Reyes. From the camp on San Pedro Creek, the Captain and his men followed the beach to the north, then entered the hills and from the summit beheld the great estuary.

Three days of slow travel brought the expedition to the site of modern Palo Alto where a new base camp was made to await Ortega's probing of the east side of the estuary. Ortega returned in four days with discouraging news. He had encountered aggressively hostile Indians and had observed great stretches of burned-over land leaving no pasture for the expedition's livestock. A council was then called and the decision was made to return to San Diego.

On the return trip, the Portolá Expedition found Monterey Bay.

The San Francisco region was further explored by Lieutenant Pedro Pagas in 1772 and by Juan Bautista de Anza in 1776. The importance of the inland bay was further emphasized by the establishment of a presidio and two missions in the environs of the bay.

Adapted from the NRHP nomination.