Morlais Tunnel was opened in 1879 by the London & North Western Railway to connect to the Brecon & Merthyr Railway, the 1,040 yard tunnel reaches a depth of 80ft. It is double track throughout its length. It was closed in January 1958. It has three ventilation shafts, 2 of which are located in the Brecon Mountain Railway car park in its Pant station. It was explored by myself and Perry my dog.