The Exeter Secret Tunnels are a major mystery as they have never actually been found or discovered, they have only been rumored to exist. The story goes back a long time and the tunnels are said to be linked to the Underground Railroad. Robbins Paxton Gilman even tackles the legend on these tunnels in his narrative: The Old Logg House by the Bridge.
The secret underground tunnels have been rumored to be near Franklin & Clifford Street. Legend has it that the tunnels intersect in the basement of the Gilman Garrison house which was constructed in 1709. The US Department of Interior undertook a project to document and survey the house. Their research has never been publicly revealed!