St Asaph is a cathedral city and community on the River Elwy in Denbighshire, Wales. At the 2021 census the community had a popul…St Asaph is a cathedral city and community on the River Elwy in Denbighshire, Wales. At the 2021 census the community had a population of 3,485, making it the second-smallest city in the United Kingdom in terms of population. It was historically in Flintshire.