Conwy Castle across the Conwy Estuary.

We have travelled up to North Wales for my mother in laws 97th birthday celebrations and on the way, we could see the castle across the Conwy Estuary. It was quite a magnificent sight being in full sun and the estuary being full due to a high tide. The castle was built between 1283 and 1289 and cost £15,00 to construct (what would that equate to now I wonder?)