Golden Gate Bridge: The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the strait between San Francisco and Marin County to the north. The bridge took seven years to build, and was completed in 1937.
Alcatraz: Surrounded by the freezing water of San Francisco Bay, Alcatraz was believed to be inescapable. Today, the island is a popular San Francisco tourist attraction and a historic site. It is operated by the National Park Service and is open to tours.
Golden Gate Park: The Golden Gate Park is a large urban park with windmills, bison, museums, lakes and a carousel among its many attractions. A popular tourist attraction is the Japanese Tea Garden with beautiful plants, ponds, bridges, and Japanese-style structures including a tea house.
Transamerica Pyramid: Located in the heart of the Financial District., the Transamerica Pyramid is San Francisco’s other famous icon besides the Golden Gate. According to its architect, William L. Pereira, a pyramid is the ideal shape for skyscrapers, offering the advantage of letting more air and light in the streets below.
Palace of Fine Arts: The only structure remaining from the 1915 World’s Fair, the Palace of Fine Arts features a classical Roman rotunda with curved colonnades situated in an idyllic park setting with a classical European-Style lagoon.
Source: http://www.sanfrancisco.com/attractions/