Most Familiar, Least Known Place

This is my nomination for the most familiar but least known place in London. It's the Polish War Memorial, on a roundabout above the A40, commemorating all those Polish Airmen who fought in the RAF and lost their lives in WW2. Best known, becasue it appears on traffic reports each morning "There's a ten mile jam back to the Polish War Memorial". Least seen because you can't see it from the road and nobody comes here that doesn't have to.