This paper presents an algorithm for occlusion culling from regions of space. It is conservative and able to find all significant occlusion. It discretizes the scene into view cells, for which cell-to-object visibility is precomputed, making on-line overhead negligible. Unlike other precomputation methods for view cells, it is able to conservatively compute all forms of occluder interaction for an arbitrary number of occluders. We describe an application of this algorithm to urban environments. A walkthrough system running an 8 million polygon model of the city of Vienna on consumer-level hardware illustrates our results.