What's the noun for concourses? Here's the word you're looking for.
concourse
A large open space in or in front of a building where people can gather, particularly one joining various paths, as in a rail station or airport terminal, or providing access to and linking the platforms in a railway terminus.
“Contained within the envelope is a series of floor plates set around a dramatic atrium that rises through the building from the main concourse on the lower ground floor.”
“The passengers simply rose from their seats and straggled down the long concourse for their free meal.”
“The concourse of diverse cultures at the trade fair created an atmosphere of global unity.”
