The AA is Britain's oldest school of architecture, but anyone can take advangte of the great work going on there. You can catch really interesting public lectures and free exhibitions throughout the year. There are also occasional installations and event launches, a bijoux cafe and brilliant bookshop. A great place to hang out with the builders of the future.
It's really close to my house and one of my favourite pubs in London! (I even went before it was close to where I lived!) It is London's first cooperatively owned pubs and has lovely events and workshops, exercise classes and great parties, and good beer! It's lovely in the beer garden in the hot summer and equally great in the winter, next to a real fire.