The Golden Gate Bridge needs no introduction, but it deserves one anyway. The 1.7-mile suspension bridge spanning the mouth of San Francisco Bay is one of the most beautiful structures ever built -- its International Orange towers rising out of the fog are the defining image of the city.
Walking or cycling across is free and takes about 30 minutes on foot. The east sidewalk is open to pedestrians during the day; cyclists use the west side. Start from the south (San Francisco) end, where the vista point and the Welcome Center offer the classic views. For a longer outing, continue across to Sausalito and take the ferry back. The bridge is spectacular in any weather, but on a clear day the views up and down the coast are extraordinary.
The best vantage points for photographing the bridge include Battery Spencer and Hawk Hill in the Marin Headlands (north side), Fort Point directly beneath the south tower, and Crissy Field along the Presidio waterfront.