San Francisco is 3 times larger than Alexandria, Virginia.
Area: 40 km2 calculated
Alexandria is an independent city in the Commonwealth of Virginia. As of the 2010 census, the population was 139,966, in 2013, the population was estimated to be 151,218. Located along the Western bank of the Potomac River, Alexandria is approximately six miles south of downtown Washington, D.C. Wikipedia
Area: 122 km2 calculated
San Francisco, officially the City and County of San Francisco, is the cultural center and a leading financial hub of the San Francisco Bay Area and Northern California. Wikipedia