Developed in the late 1940's, the Curta Hand-Held Calculator was at the same time the most advanced and also the last mechanical calculator invented and marketed. Invented by Curt Herzstark when he was a prisoner at Buchenwald (a German concentration camp), this calculator is run entirely by gears, knobs, and levers.

It was made in Liechtenstein, and was produced and marketed from 1947 until 1970, and sold until 1973, at the price of approximately $120. It was at this point that pocket calculators began selling at affordable prices, and even the mechanically advanced Curta could not compete with them.

For More Information, check out these links:
The Curta Calculator Page
Disassembling A CURTA!
The Amazing CURTA!