Beaminster Tunnel or Horn Hill Tunnel is a 345-foot-long (105 m) road tunnel on the A3066 road between Beaminster and Mosterton in Dorset, England. The tunnel was constructed between 1830–1832; it was one of the first road tunnels built in Britain, and is the only pre-railway road tunnel in the country still in use. It was built to take a toll road underneath a steep hill to the north of Beaminster and make it easier for horse-drawn traffic to travel from the coast to the hinterland of Dorset. It underwent significant repairs in 1968 and again in 2009, but in 2012 a torrential rainstorm caused a landslide that resulted in the partial collapse of the tunnel's north entrance and the deaths of two people.