Pigeon Key Historic District, Former railroad construction base in Monroe County, United States.

Pigeon Key Historic District covers a small island at mile marker 45, just east of Moser Channel, where the old Seven Mile Bridge crosses above it. The district holds 11 historic buildings and 3 structures, several of them dating from Henry Flagler's Overseas Railroad construction era. A rare three-way bridge, now partly abandoned, also stands on the island.

During construction of Henry Flagler's Overseas Railroad Key West Extension, Pigeon Key held a major construction depot, the jumping-off point for building the Seven Mile Bridge. The island appears as "Cayo Paloma" on many old Spanish charts. The historic district, with 11 historic buildings and 3 structures from the Flagler era, was designated on March 16, 1990.

The name references the bird species that inhabit the island. Today visitors can explore exhibits that show how construction workers lived and worked here, connecting the massive railway project to the personal experiences of those who built it.

You can reach the island by walking or cycling across the restored Old Seven Mile Bridge from the mainland. The site is exposed to sun and wind, so wear sunscreen and bring water during warm months.

The island appears as "Cayo Paloma" on many old Spanish charts, and it is said to be named for the large flocks of white-crowned pigeons that once roosted there. A rare three-way bridge, now partly abandoned, also stands on the island.