When you want a quiet, fairly formal setting for lunch, there's the Regent's Room on the 2nd Floor of the CUB (go up the stairs from the CUB west entrance). Reservations are not required, but are a good idea.

The food is simple: salads, sandwiches, fish and chips, etc., but a cut above the steam-table fare in the cafeteria downstairs. Service can be slow at times.