where was how green was my valley filmed

The film "How Green Was My Valley" (1941) was not filmed on location in Wales due to World War II making it impossible. Instead, the studio built an elaborate 80-acre set that replicated a Welsh mining village in the Santa Monica Mountains near Malibu, California, specifically at Brent's Crags (now known as Malibu Creek State Park in Calabasas). This set was designed to authentically evoke the look of Welsh mining towns based on villages such as Gilfach Goch, Cerrig Ceinnen, and Clyddach-cum Tawe. The filming took place there to capture the essence of the story's South Wales coal mining community setting. The film was shot in black and white, and the village set included architectural details to recreate the feel of the Welsh valleys authentically.