On the High Line, first published in 2012, is an engaging guide to everything a visitor sees when strolling through the park: the innovative gardens and their thousands of native and exotic plant species; the architecture, both old and new, industrial and residential; and a neighborhood whose colorful history includes the birth of the railroad, the Manhattan Project, S&M clubs, and the legendary Tenth Avenue Cowboy. In 2014, the final half-mile section...