Collectors wishing to see the 1870-S $3 gold must make a special trip. This unique coin is housed at the ANA's Money Museum. It's on display with a wonderful collection of $3 gold pieces, the Bass Collection. The coins are mounted so it's easy to examine each one.
I saw this coin in 2006. Because of its extreme rarity, and possible because it's part of a not-very-popular set, the 1870-S $3 gold does not get the publicity that other rarities may get. This coin was sold in 1982 for over $687,000, as part of the Eliasberg Collection. Wonder what it would sell for now!
Rumor had it that a second specimen was placed in the cornerstone of the San Francisco Mint, but I believe this has been disproven.
Any $3 gold is a scarce coin. Owning even one is an accomplishment. Assembling a set of these coins is truly big-league collecting. There is a complete set on display at the Money Museum, including that unique 1870-S... a remarkable, beautiful little coin.