Golden Gate Bridge is an internationally acknowledged iconic symbol not only of California, where it is built, but also of the United States. The suspension bridge is one- mile wide and three-mile long channel and links San Francisco peninsula from its norther tip to the Marin County across the strait. The Golden Gate Bridge is believed to be the beautiful and certainly the most photographed, bridge in the world. The orange colored bridge, with its 4200 feet main span, was the longest suspension bridge in the world until 1964. Although surpassed by some bridges across the world, it is still the second longest in the United States. It has been designated as one the Wonders of the Modern World by the American Society of Civil Engineers. The bridge was opened to public on May 27, 1937. The opening celebration lasted a week and over 200,000 people had crossed it either on foot or roller skates until the day before it was opened to vehicular traffic.
Known earlier as Boulder Dam, Hoover Dam, a concrete arch-gravity structure, is built in the Black Canyon of the Colorado River. It is located near Boulder City, Nevada, close to the border of the states of Nevada and Arizona. The construction, started in 1931, was completed on 1st March, 1936, two years ahead of scheduled date despite massive difficulties and Great Depression. The construction involved the use of some unproven technologies, labour of thousands of workers and the loss one hundred lives. The dam was dedicated to the nation by President Franklin D. Roosevelt on September 30, 1935. Currently, Hoover Dam is an important tourist destination and draws approximately a million visitors every year.
Built in Seattle Centre and known as an icon of the city, Space Needle is actually an observation tower. A landmark of the Pacific Northwest, the monument was built specifically for the 1962 World Fair, wherein it attracted more than 2.3 million visitors and its elevators lifted approximately 20,000 people every day. Space Needle is 605 feet tall and 138 feet wide. It is so strong that it can resist winds of up to 200 miles per hour and earthquakes of up to 9.1 magnitude. The building is equipped with 25 lightning rods or lightning conductors to secure it against the impact of lightning strikes. The Seattle Space Needle also has Sky City Restaurant at the height of 500 feet. A rotating observation deck 20 feet above it commands panoramic views not only of the downtown Seattle skyline, but also the Olympic and Cascade Mountains, Mt. Rainier, Mt. Baker, Elliott Bay and several islands surrounding it.
Located near Keystone, South Dakota, Mount Rushmore National Memorial is a sculpture carved into the granite exterior of Mt. Rushmore. The Memorial features 60 feet tall sculptures of the heads of four presidents of the United States: George Washington, Thomas Jefferson, Theodore Roosevelt and Abraham Lincoln. The national monument is spread over an area of 1,278.45 acres area. It stands at the height of 5,725 feet above the sea level. The idea of carving the sculptures was conceived by Doane Robinson, a South Dakota historian with the aim to promote tourism in the area. Mount Rushmore Memorial has acquired an iconic status in the country and draws over two million visitors every year.
Built on the National Mall in Washington DC, the Washington Monument is an obelisk - a tall four-sided narrow tapering monument like ancient Egyptian pyramids. It was constructed in the memory of George Washington, the commander-in-chief of the Continental Army and the first president of the United States. The memorial is built with marble, granite and bluestone gneiss, a kind of strong rock. Conceived by architect Robert Mills in 1840s, the construction of the monument started in 1848 and concluded in 1888, in 40 years. The work in between was interrupted due to the American Civil War. The monument was officially opened to public on 9th October, 1888. Spanning a height of 554 feet, the historic landmark remained the tallest monument and also the tallest obelisk structure in the world until 1889, when the Eiffel Tower of France overtook it. The monument was damaged by the Virginia earthquake and Hurricane Irene in 2011. It was repaired for 32 months and reopened to the public on May 12, 2014.