CT / Underground41.96° N
72.75° W
Verified July 2026

Old New-Gate Prison & Copper Mine

East Granby, CT · Connecticut River Valley

A colonial copper mine later used as Connecticut's first state prison, with underground workings and surviving prison ruins.

Field note

Public access is controlled by the state museum. Underground availability can change, so confirm before driving.

Access warning

Stairs, low light, and uneven historic surfaces. Follow staff directions.

Evidence line

This listing is marked documented. Practical details were last checked in July 2026. Conditions change, so use the primary source before leaving home.

Check the source: Connecticut State Museums