A national monument near Flagstaff will be closed for two days while a helicopter delivers material to widen a trail.
Walnut Canyon National Monument will be closed to visitors Thursday and Friday. It's about 10 miles southeast of Flagstaff.
Rock and other material will be transported via long-line helicopter to the Island Trail that's 185 feet below the canyon rim.
The trail is about one mile round-trip and takes visitors past more than two dozen ancient cliff dwellings.
About 300 people visit the monument during the weekdays this time of year.