The Washington Monument is made of marble from three different quarries, none of which were in Marble, CO. These are the Cockeysville Marble from quarries in Maryland, Sheffield marble from Mass, and marble from Texas.
Marble from Marble, CO was used in the Tomb of the Unknowns and for parts of the Lincoln Memorial.
There is a great barbecue restaurant in Marble! Slow Groovin' BBQ is the name, I think. I took my Ram truck up the trail from Marble to the Crystal Falls Mill. It is spectacular in the fall. If I drive the trail again, my wife and I will probably rent a side-by-side four-wheeler. There were times that there was NO margin of error with my truck. Still, Marble is cool and the trail out to the mill was fantastic.