The study rates 24-hour city San Francisco tops, followedclosely by New York and Boston, with Los Angeles and Washington, DCon their heels. Atlanta, which ranks 12th, is one of the 9-to-5cities in the same category with Phoenix, Philadelphia, Dallas andDetroit.

Investors do well in Atlanta, the study notes, but view themarket as more risky than a 24-hour city, where demand oftenoutstrips supply. Twenty-four-hour cities with an exciting centercity combination of residential, business, capital, entertainmentand shopping head the list.

Add to that mix, interesting topographic features andneighborhoods with character, the infrastructure for technology,mass transportation, lowered crime rates and an immigrationpopulation for the labor pool. Investors also like cities wheresupply is limited by geographic features, thus forcing aconcentration in an urban core.