What was the masterpiece of modern architecture in the 20th century?

The work known as the pioneer of modern architecture in the 20th century was the National Museum of America in Washington, D.C., also known as the Hermitage Museum. The building was designed by the American architect Paul Gettys from 1962 to 1965. It is a museum with more than 200 exhibition spaces and is one of the most important museum in the United States. The unique geometry of the building and the use of glass materials made it a classic in the modern architectural world.