3) Golden Gate Bridge, San Francisco
San Francisco’s Golden Gate Bridge is one of the most recognized bridges in the world. Construction began in 1933 and the bridge opened in 1937, linking the city with Marin County, to the north. At 4,200 feet, it was the longest bridge until 1964, and the 746-foot towers made it the tallest until 1993. In 1994, the American Society of Civil Engineers named it one of seven civil engineering wonders of the United States. It has six lanes for vehicles, and each side has a pedestrian lane for bikes and walking. Visitors can head to the Welcome Center and Plaza to see exhibits about the construction and free walking tours are offered twice a week. Each end touches portions of the Golden Gate National Recreation Area where you can take a long hike in Muir Woods, stroll along Stinson Beach or go whale-watching along the shoreline in the Marin Headlands. Around 18 million people visit each year, with both sides of the bridge having many great views and attractions.