Forbes has compiled a list of the most expensive real estate blocks in 10 major cities. It teamed up with date provider Reply! to compile an index of the 'billionaire rows' of the US. In New York, the block between Fifth Avenue, Madison, 69th and 70th Sts. takes the crown. In Boston, it's a private square on Beacon Hill, and in L.A. it's a block just above Sunset Blvd.
To generate the list, Forbes and Reply! came up with the 100 most expensive properties in each city, put them on the map, then sized up home values and the density of pricey homes in each agglomeration. Recent buying activity and construction helped buoy blocks to the top. The top asking price on San Francisco's most expensive? $65 million.