Reddit reviews Mabinogion (Everyman's Library)

I'm going to suggest somewhere completely different: Wales. There are a lot of ancient Celtic ruins in that country, and most of them are not promoted to tourists. The Welsh island of Anglesey was the last stronghold of the Druids in their fight against the Roman Empire, and there you can find the ruins Din Lligwy village, about 2000 years old. Take the #62 bus from Bangor and ask the driver to let you off at the crossroads that leads to Moelfre, then walk down the farm road ahead, past the Stone Age cromlech tomb, and over the hill until you see the site spread out before you. If you are alone, which it's likely you will be, spend time with the stones and think of the daily life that took place ages ago.

Wales is full of places like this. Accessible yet deserted, surrounded by remote picturesque settings.

To set the mood, it helps to read the old stories like The Mabinogion. Even more helpful is to try to learn the local language and make friends; they might tell you about places that aren't publicized. Or just go wandering -- one time we stopped the car near a footpath on the Gower peninsula; on the other end of that path, beyond a woods, was a deserted crumbling castle perched on a cliff above the ocean.

Just one suggestion. Several people I knew who came from the area around those ruins stepped into them with their right foot first. When I asked, they'd joke about how it was just a superstition they'd been told by older relatives. But they all did it. Maybe you should too.