Bannerman Castle (Pollepel Island)

Francis Bannerman VI, a Scottish-born arms dealer, couldn't legally store thirty million surplus military cartridges from his post-Civil War business in his Manhattan storefront. So in 1900 he sketched a medieval fortress from memory of his childhood in Scotland and handed the drawings to builders with no architectural training. The walls lean and the proportions feel slightly off, which is somehow perfect for a place born from a businessman trying to solve a cartridge overflow problem. But Bannerman was also a showman. He built the castle as a warehouse and a billboard at once: BANNERMAN'S ISLAND ARSENAL is still cast in giant letters into the western wall, an advertisement for his mail-order surplus catalog, visible to every boat and train running up the river.

The island's scars and its rescue

Construction ran from 1901 until Bannerman's death in 1918. Then disaster: an explosion in 1920 tore through an ammunition building, and another fire in 1969 burned away the roofs and floors entirely, leaving only the walls standing. For decades, the castle sat abandoned until the nonprofit Bannerman Castle Trust began stabilizing and restoring it. Their work became the only public path onto the island: we reach it only through the trust's seasonal tours, and there's no private dock or kayak option.

The guided tour from Beacon

Tours run May through November, departing from the dock across from Beacon's Metro-North station. The Estuary Steward takes us 30 minutes up through the Hudson Highlands, then a guide leads a 45-minute walk through the castle ruins, the restored family residence, and the grounds. We get 45 minutes to explore on our own before the return voyage. New for 2026, Wednesday and Thursday summer tours now include access to the Grotto, a stone garden feature that was sealed off for three decades and only recently reopened.

Wear shoes that grip gravel and dirt; the island has no pavement, and the walking is genuine. Weather can bump a sailing, so check a marine forecast the morning of your visit.