Where was The Secret filmed?
1974 film by Robert Enrico
The Secret (1974) was filmed in Genestelle, Mimizan and Château de Craux, 3 places named in its Wikipedia article, in France. Wikidata records no filming location for it at all, so the article is the only recorded source. Each place says where its claim comes from.
Places per Wikipedia's article
The Wikipedia article names 3 places. Each links to the sentence that says so.

