Also near 215th Street is the majestic flight of 110 steps, which evoke the Rue Foyatier in Montmartre. The steps connect Broadway with Park Terrace East, Isham Park and farther west, Inwood Hill Park (and supposedly the site of the storied $24 purchase of Manhattan from the Indians).

The park, on a schist ridge 200 feet above the Hudson, is home to Manhattan’s largest remaining forest and where caves attest to the most ancient habitation in New York from pre-Colombian times to seasonal camps occupied by the Lenape people as late as the 17th century.

Not surprisingly, many of Broadway’s more familiar, and oldest, landmarks are concentrated in the miles that begin at the southern tip of Manhattan, Professor Leadon’s Mile 1, where the Dutch settled New Amsterdam four centuries ago.

Broadway (originally Heere Straat, or High Street, then Brede Wegh, or Broad Way) got its name because it began at the expansive 17th-century ramparts of Fort Amsterdam, which commanded a hill that sloped down to Bowling Green, Manhattan’s oldest park (another rumored site of Peter Minuit’s $24 deal).

The tiny greensward was surrounded by a cast-iron fence — it still stands — to prevent vandals from desecrating the equestrian statue of King George III, which was toppled in 1776.

“Certainly, the first half of Broadway, as it developed, was without question the economic engine of the city,” Professor Leadon said. “And, it’s the city’s spine, the thing that unites and divides” — downtown, the snootier “dollar side” to the west versus the cheaper “shilling side” in the early 19th century; and in Washington Heights, the Jews to the west and Dominicans to the east more recently).