The wide, open area that's either inside or in front of a building is called a concourse. A concourse is often located where many paths or hallways meet.
Many kinds of buildings have a concourse, including train stations, airports, hotels, and shopping malls. Concourses are large enough for many people to congregate there — and this crowd or gathering of people can also be called a concourse. A movie star visiting a small city might find himself surrounded by a huge concourse of fans asking for autographs. The Latin root is concursus, "a running together," and the word's original sense was "the flowing of a crowd of people."