Ceulanamaesmawr is a parish in Cardiganshire to the north-east of Aberystwyth. The main settlement is the village of Tal-y-bont. The parish is bounded by Llangynfelyn and Ysgubor-y-coed to the north, Cadfarch in Montgomeryshire to the east, Blaenrheidol to the south-east, Trefeurig to the south and Tirymynach and Geneu'r Glyn to the west. It had a population of 983 according to the 2001 census.
The name of the parish is dervied from that of the two rivers Ceulan and Maesmawr, both tributaries of the Eleri, the river that flows through Ceulanamaesmawr.
The village grew to be a thriving industrial centre during the middle of the nineteenth century when woollen mills were established on the banks of the Ceulan and Eleri rivers and with the opening of numerous lead mines in the surrounding valleys and hills.