Kryptos
Although not theorized to be made by aliens or other supernatural elements, Kryptos has baffled brilliant codebreakers all over the world for over three decades.
Jim Sanborn created Kryptos and placed the sculptures on the grounds of the Central Intelligence Agency in Langley, Virginia. Three out of the four sculptures have been solved but the last one remains a mystery.
The sculptures are made of copper plates, granite, quartz, and wood. We wonder how much they paid the moving company to move all four of these.