What is the Pentagon?
It is the headquarters of the United States Department of Defence for army, navy and air force services. It is a large five-sided building in Arlington county in Virginia, near Washington, DC.
On its completion in 1943, it was the world's largest office building, covering 14 hectares and offering 343,730 square metres of floor space for as many as 25,000 people.
The building consists of five pentagons (a shape with five sides). The five 'rings' have 10 spoke-like corridors connecting them.
A huge concourse within it provides a shopping centre for Pentagon workers. Parking areas around the building can accommodate as many as 10,000 cars. A heliport was added in 1956.
How do ballerinas dance on their toes? Doesn't it hurt?