by Suzy Strutner: You know about the seven world wonders, and you know about U.S. national parks…

But U.S. national monuments are a whole other class of beauty that, to be honest, we never realized was missing from our bucket lists.

President Theodore Roosevelt started the U.S. national monument program in 1906, when he chose Devil’s Tower in Wyoming as the first. Presidents and Congress can establish sites of “historic, prehistoric or scientific significance” to join the list:  Barack Obama named three new ones earlier this year. U.S. national monuments now number well over 140, including striking historic sites like a Maryland landscape dedicated to Harriet Tubman’s Underground Railroad and dazzling natural wonders like the Grand Canyon.

Here are some of the most beautiful, little-known U.S. national monuments, just in time for a late summer road trip.