Petaluma is a city in Sonoma County, California, in the United States. It is estimated that the 2006 population was 54,660 Located in Petaluma is the Rancho Petaluma Adobe, a National Historic Landmark. It was built beginning in 1836 by General Mariano Guadalupe Vallejo, then Commandant of the San Francisco Presidio. It was the center of a vast 66,000 acre (270-km²) ranch stretching from Petaluma River to Sonoma Creek. The adobe is considered one of the best preserved buildings of its era in Northern California. Petaluma is a transliteration of the Coast Miwok phrase péta lúuma which means hill backside and probably refers to Petaluma's proximity to Sonoma Mountain. Petaluma has a well preserved, historic city center which includes many buildings that survived the 1906 San Francisco earthquake.