10 Dollars 2006 Pisa Tower

Nauru — eight square miles of phosphate rock in the central Pacific — briefly became one of the world's wealthiest nations per capita during the phosphate boom of the 1970s and 80s, then lost nearly everything through a combination of resource depletion and catastrophically mismanaged sovereign investment funds. By the 2000s, the government was issuing novelty collector coins almost exclusively for the foreign bullion market, a revenue stream that had nothing to do with domestic circulation and everything to do with staying solvent.

The applied gilt metal tower is the distinguishing feature of the KM#42 type — a three-dimensional attachment rather than struck relief.