Aztec Ruins National Monument, N.M.
Most visitors here admire the remnants of a lost civilization. Fred Blackburn studies the graffiti.
–“There’s some good stuff here, Fred,” Zoe Matney, an assistant, called to Mr. Blackburn one afternoon in early October from atop scaffolding in a 900-year-old room. She wiped away dust to reveal a signature on a wooden ceiling beam.