National Park Service, Associated Press
This undated photo provided by the National Park Service shows as petrified logs erode from the badlands, they tumble down to the base of the hills in the Petrified Forest National Park in Arizona.

FLAGSTAFF, Ariz. — The buildings at Petrified Forest National Park are held up as an example of modern architecture with their flat roofs, low silhouettes and large windows that open up to the vast expanse of rainbow-colored desert.

The National Trust for Historic Preservation recently designated the Petrified Forest compound a national treasure because of its architectural significance.

The roughly 35 buildings were part of the National Park Service's Mission 66 program, a 10-year effort starting in 1956 to introduce modern architecture before the agency turned 50.

Superintendent Brad Traver says he hopes to bring attention to the buildings with an exhibit that will explain its history and the plans to rehabilitate them.

The complex is visible from Interstate 40, about 25 miles east of Holbrook.