RCW 49 is powered by Westerlund 2, a compact rich cluster with a dozen early type O stars, 20 later type O stars, and 2 WR stars. It has multiple very strong stellar wind sources which must control the dynamics. The cluster is older than Orion (~2 Myr) and yet the bubble is still very compact. It looks like it has broken open but the opening is still quite small. The bubble is also much more fragmented with photodissociation region (PDR) structures strongly sculpted by winds, radiation pressure, ionization fronts, instabilities.