Tremadog was a town created by William Madocks (1773-1828) in the first decade of the 19th century on reclaimed land known as Traeth Mawr, the estuary of Afon Glaslyn. It was originally intended to be a post town on a direct road between London and Dublin, via Porthdinllaen on the Lleyn peninsula, a project that in due course lost out to the Holyhead Road.

The Market Hall was an integral component of the original planned town and was begun in 1807. The hall is 2 storeys, built of coursed stone, with 5 tall, round-headed porches decorated in coape or terracotta. It was originally open-fronted in the lower storey, and incorporated a dance hall and theatre in the upper storey.

Arches in the lower storey were infilled with ironwork by Clough Williams-Ellis in the 20th century, but it was replaced by the present glazing in the 1970s.

Reference: Cadw listed buildings database.