One of the castles overlooking Swansea Bay is Oystermouth Castle in Mumbles, the village of the rich just outside of the city of Swansea. Oystermouth Castle has a thousand-year-old history, although the present castle of stone has only been standing for around 800 years (and underwent refurbishment, meaning they added a few things like a visitors and education centre and removed the overgrown plants, in 2009).
For the first few hundred years, it changed hands between the Normans/English and the Welsh before coming into the hands of successive, even more powerful families, which expanded, fortified and made the castle more beautiful, surpassing nearby Swansea Castle and often being the main residence of said families.
Nowadays the Castle is open from the Spring to the Autumn and features fantastic views of Swansea Bay and Mumbles.
How to visit
Oystermouth Castle is located in the Mumbles and you can find more information about its current status here. Generally the castle is open every day and you can buy tickets at the door (pre-pandemic). Tickets are about £4 for adults.
You can get here either via a local bus or by car. Parking is available but difficult to find in Mumbles; there are some parking spots meant for visitors near the castle.