If you use "stand-alone" Wireless Access Points then, yes, they would each have to be wired back to the main router, or to a network switch wired back to the main router, but which could be located in one of the halls. Wireless Access Points cannot communicate wirelessly with one another.
Stand-alone Wireless Access Points tend to be expensive and an alternative method might be to use Cable/DSL Routers (often less expensive), which don't incorporate a modem, but do incorporate a Wireless Access Point. Using this method, a Cable/DSL router would be connected via its WAN port to one of the main router's LAN ports. Computers could then connect "wirelessly" to this second router (in hall no1?).
A second Cable/DSL Router could then connect in the same way to the first Cable/DSL Router, i.e. its WAN port to one of the first router's LAN ports. Repeat the procedure to connect a third Cable/DSL Router to either the first or the second Cable/DSL Router.
With this scenario, all of the routers would have to operate in different subnets (IP address ranges) to avoid address conflicts. This also means that only computers connected to the same router could share Folders & Printers, if that's important.