Desert View Watchtower looks as if it’s been standing on the edge of the Grand Canyon for 1,000 years. Rising 70 feet, the circular stone structure appears to emerge straight out of the Earth, as naturally as the junipers growing nearby along the rim.

The watchtower is perfectly imperfect, the product of architect Mary Elizabeth Jane Colter’s obsessive attention to detail and her use of uncut stones found nearby, each placed just so to create the shadows and textures she was seeking. “Time, the lost principle in much modern construction, was taken to select each rock for the outer walls,” Colter would write in her Manual for Drivers and Guides, a detailed document she created to answer questions Grand Canyon tour guides might have about the tower.

Colter bristled at the notion that the tower was a reproduction, replica or copy of any single structure. Nor did she want visitors to think it was a restoration of an existing Ancestral Puebloan building that had stood on...