The oldest railway tunnel of any appreciable length in the country. The 674yds (616mts) long tunnel was built and opened in 1816 by The Brecon to Hay Tram road, which was a horse drawn "plate way". In 1862 work commenced to enlarge the tunnel to take a single road standard guage railway, this work was completed in three months allowing the first train to run through the tunnel on the 1st January 1863, with the first passenger train travelling through on the 2nd of May that year. The tunnel is straight and on a very slight gradient, with thirty personnel refuges built in the walls at regular spacings. Because of the need for a set of points to be situated at the mouth of the tunnel in order to serve both platforms, a unique signaling system was fitted inside the tunnel. The portal at the east end was at the end of the station platform, the west end is in open country side. Both ends of the tunnel have been blocked up and are now on private property.