A now disused tramway tunnel that once ran for c. 75m below an Italian styled garden and appeared near the modern library. The tunnel is shown on a map of the forge dating from 1834, again on the Town Plan map of the 1870's and on each 25" Ordnance Survey Maps from 1882 to 1921. Although initially being opened as a tramway tunnel as part of a network to transport minerals down the valley, the tramway was converted to standard-gauge railway by 1855 to carry both mineral and passenger traffic.

Pontypool: Understanding Urban Character, Cadw 2012

Ross Cook, RCAHMW. 22nd February 2013