SPIRE ON THE PLAINS: Early overland westward emigrants often wrote in their journals about the awe-inspiring Chimney Rock in the North Platte River Valley. Chimney Rock, rising 480 feet above the valley below, with a spire rising 325 feet above the conical base, could be seen up to 30 miles away. Today, Chimney Rock National Historic Site is much like it was in the 19th century, with few modern developments surrounding the landmark, and a visitor center telling the history of this most notable Nebraska monument.