Forbes reported on some of the most expensive blocks in the US. They put together some research on homes that have sold in larger cities and found that the higher end homes tended to concentrate around major city features. Some of the cities included: New York, Miami, Chicago, San Francisco, Washington D.C, and Seattle. Some homes averaged $65 million.
As usual in real estate, location was a major determining factor. Many wanted a view; many wanted proximity to hot entertainment or other city features.
They also have pictures of the homes and areas. Check them out.