The overall cost of the building's construction and display installations is $540 million. The Smithsonian Institution and the federal government both contributed to this sum. The building was designed by British architect Sir Norman Foster and constructed by the Washington Building Center. Its 9,000 square feet (900 m²) of floor space include a grand atrium filled with sunlight from high-powered glass walls that open during the day for natural light and close at night to preserve museum security and exhibit integrity. The museum also uses energy-efficient lighting and heating/cooling systems. The building was completed in 2004 after more than five years of planning and development. It replaced the original 1975 National Museum of American History, which was then considered to be too small to accommodate all of the museum's collections-related activities. The new museum has 22 exhibition halls, three theaters, and two rooftop gardens. It covers 70,000 square feet (6,500 m²) of gallery space, making it the largest museum in America. The new facility includes more than 400 objects or sites being displayed during its opening year of 2005. These include items such as George Washington's sword and gun carriage, Harriet Tubman's horse, and an early American schoolhouse.