This is a wonderful garden, with superb views over the city. It's unusual in that it deals only with plants from Mediterranean climates: Spain, California, Chile, Australia, the Canary Islands... It's a bit tricky to get to, especially due to construction (as of May 2009). It's right across the street from the Olympic Stadium. Reasonable parking, no food other than a vending machine (I think...) Inexpensive!
Please note: the paths are all wheelchair navigable, but these gardens we built into the hillside, so the paths change elevation. Lots of walking, not much shade. Fabulous in March!