Mucking around in the CoDRadiant editor...

Creating a belfry (bell tower) with stairs and wooden support beams and platforms.
Call of Duty: BelfryA - bottom floor Call of Duty: BelfryA - Middle platform
Call of Duty: BelfryA - Upper portion Call of Duty: BelfryA - Top level (unfinished)
Call of Duty: BelfryA - Wireframe model

Multi-level parking garage:
Call of Duty: Multi-level parking garage (caulk texture)

16 foot wide rowhouse (modeled on the one I live in)
Call of Duty: Row house - basement Call of Duty: Row house - basement spawns
Call of Duty: Row house - first floor Call of Duty: Row house - first floor
Call of Duty: Row house - entrance hallway Call of Duty: Row house - third floor
Call of Duty: Row house - second floor

Spiral Tower A - Crazy, blocky, with a spiral ramp around the outside.
Call of Duty: Spiral Tower A Call of Duty: Spiral Tower A
Call of Duty: Spiral Tower A

Spiral Tower B - A bit more realistic, still using a ramp instead of steps.
Call of Duty: Spiral Tower B Call of Duty: Spiral Tower B
Call of Duty: Spiral Tower B Call of Duty: Spiral Tower B