Back in 1980, LEGO employees who had worked in the LEGO factory in Hohenwestedt, Germany for 25 years were awarded with an official LEGO brick created out of 14k solid gold.
This was also given to a select few business partners within the span of 1979-1981.
It may be a thing of the past, but this gold LEGO brick still remains the most expensive LEGO one can buy.
The last transacted LEGO brick was sold for USD$14,449.99 on Brick Envy, an unofficial LEGO store.
The brick weighs 25.65 grams, and is made of 14K gold (0.8246 troy oz). It is the same size and shape as the original 2x4 LEGO brick.