The story of great real estate investors is a tale of superb salesmanship, public relations, politicking, dealmaking, risk taking and creative financing. Manhattan has by far the greatest concentration of real estate value in the U.S.; fortunes have been made there by the likes of John Jacob Astor, Harry Black, Fred French, William Zeckenforf, and Harry Helmsley. Other U.S. real estate tycoons include William Levitt, Trammell Crow, and Donald Bren. These investors have been shrewd manipulators of mortgages, down payments, and cash flows-though occupancy rates, tax structure, and government assistance have frequently been vital parts of the recipe for real estate success. An unusual investment category is that of collectibles (sometimes known as 'portable wealth') - for which value depends on sentiment and other intangible factors. For the hobbyist, collectibles forge a link with the past, with far-away places, or with well-known people; a collection is a kind of tangible memory. Collecting also satisfies a human desire to own the best, the most, or the only specimen of things that are sought by others. Coins, stamps, baseball cards, and the various decorative arts (e.g. paintings, sculpture, antiques, ect.) all have proven to be popular with investors. Collectors seek not only a chance for a return on investment-but also the sheer joy of owning some of the finer things of life.