The Frontier class starbase was the largest deep space station in operation in 2385. At normal capacity, it supported a population of 13,000 and was capable of taking on the passengers and crew of dozens of ships that made dock.
It was made up of three intersecting rings, perpendicular to each other, with a central spherical core. The rings housed docking facilities, repair bays and cargo bays, as well as sensor arrays, shield generators and weapons ports. The operations center, informally known as the Hub, was located at the upper intersection of the two vertical rings. (DS9 - The Fall novel: Revelation and Dust)