This paper proposes a scalable architecture for multimedia streaming in wireless LANs. Current IEEE 802.11 WLANs can support tens of media streaming users. We propose a hierarchical approach that can support over 1000 concurrent users. Our architecture exploits several existing technologies, including multi-channel WLANs, power control, and caching. The paper first describes the system design and operation, as well as assumptions and constraints. Performance issues are then explored via simulation, using synthetically-generated media streaming workloads. The simulation results show that: 1) our design can support up to 1600 concurrent media streaming clients using current WLAN technology; 2) the system architecture is quite robust to the user-level characteristics of the media streaming workload; and 3) proper cache management can make the system operate effectively even with limited cache sizes.