Question: What was painted on the third flatiron near Boulder until it was painted over in 1980?

Answer: A white “CU” was painted on the side of the third flatiron until the city painted over it in 1980. It is still visible to keen-eyed observers.

The Flatirons are the striking, slanted, reddish-brown sandstone formations that make up a portion of Boulder’s foothills on the west side of town.