The top of Manhattan is the wildest part of it — the highest ground, the last real forest, and a medieval monastery on a cliff over the Hudson. Three and a half kilometres from one park into another, with the Middle Ages in between.
Ride the A to its deepest station and take the lift up into Fort Tryon Park, where the Heather Garden runs along the ridge. Walk west to the overlook: the Hudson below, the Palisades cliffs rising opposite, kept bare on purpose. Then the Cloisters — the Met's medieval museum, assembled in the 1930s from five French monasteries shipped over stone by stone, the unicorn tapestries hung in its halls. The building is the exhibit; go in even if you wouldn't normally.
North from there the land turns properly wild in Inwood Hill Park: caves, old-growth tulip trees, the one corner of the island that still looks as the Lenape knew it. Follow the trails down to the restored salt marsh at the top, where egrets work the reeds, then out to Dyckman Street and the express train home.

