Where? The jewel of the Cadogan Estate just off Sloane Street.
Why? Spectacular, expensive garden square, quintessentially English, great shopping.
How much? Flats £10m, houses £25m.
What the agents say: Charlie Willis, Strutt & Parker: "One of the best garden squares in Knightsbridge. With their red brick facades, these houses are less formal than their Eaton Square counterparts but equally prestigious."