Main station of the Festiniog Railway, the oldest surviving independent railway company in the world.

In the 18th century, slate mined in the mountains round Blaenau Ffestiniog had to be taken, first by pack animal to the River Dwyryd, and then by shallow-draft river boats to the sea, where it was loaded onto ships. In 1798  W.A. Maddock built a Cob, or embankment across the estuary of the River Glaslyn, which wore out channel to form a natural harbour. This harbour was called Port Madoc, known today as Porthmadog.

Shortly after Maddocks death in 1830, two businessmen, Samuel Holland and Henry Archer promoted an Act of Parliament to construct the Ffestiniog Railway. They surveyed a route down from Ffestiniog to Porthmadog, via the cob. They planned a narrow gauge railway of 23,5 inches, as used in the quarries. The loads would descend under gravity, and horses would pull the wagons back up to the mine.

The gravity/horse method of use soon came under strain, and the owners of the track looked for a solution using a narrow gauge steam engine. It took until 1863 for contracts to be signed with George England and Co., London, for the manufacture of four small locomotives. The engines were completed in 1864

Soon the volume of traffic was placing the railway under strain again. In 1869  permission was obtained to double the track. However this proved to be too expensive, so the railway engineer, Robert Fairlie,was commissioned to build a more powerful locomotive able to haul heavier trains and to get around the sharp curves and up steep gradients in the mountains. His solution was a double-bogie engine.

The Festiniog Railway Company was incorporated by Act of Parliament in 1832. The original spelling of the name was with only one 'f'. Modern spelling uses the Welsh language version with two 'ffs'. The station is built at the western end of the Cob, the great embankment across the Traeth Mawr, on a peninsula from Ynys Madoc constructed in 1842 to form a slate wharf and a harbour wall. It was opened for passenger service on 6 January 1865 and was closed to passengers on 15 September 1939 but continued in use as the principal offices of the Ffestiniog Railway Company and the home of the Manager (Mr Robert Evans) including throughout the years of almost total closure from 1 August 1946 to 24 September 1954. The station reopened for passengers on 23 July 1955.

The present stone buildings, replacing earlier wooden buildings dismantled and reused elsewhere on the railway, date from 1878/79 and the goods shed was added in 1880. They were linked to the former goods shed by way of a major extension in 1975. Passenger facilities include a booking and enquiry office, a large tourist and hobby shop and a large cafeteria with licensed bar. The erection of the platform awning was completed in 1988.

The Harbour Station is the operational headquarters of both the Ffestiniog and the Welsh Highland Railways.