DENVER (AP) -- Three Colorado sites are among the 27 spots nationwide that have been newly designated as national historic or natural landmarks.

Interior Secretary Ken Salazar said Wednesday that Denver Civic Center has been designated a national historic landmark.

Also receiving that designation is the Denver and Rio Grande Railroad's San Juan Extension in Rio Arriba County in New Mexico and Conejos and Archuleta counties in Colorado. The narrow-gauge line is now owned by the two states and operated as the Cumbres and Toltec Scenic Railroad.

Salazar says Big Spring Creek in Saguache County has been designated a national natural landmark.

There are roughly 2,500 designated national historic landmarks and 600 national natural landmark sites nationwide.