Narnia! (aka Tollymore Forest).

I used to love visiting this magical place in Co. Down when I was young, and still relish the opportunity to go for a walk there whenever I come back home for a visit.
CS Lewis was taken there often as a child and it was the inspiration for Narnia. It really does resemble that mythical kingdom - especially when the snow is on the ground.
Recently, Tollymore has been used as one of the locations for filming for the TV series Game of Thrones.