Chateau en Espagne

a castle in Spain, that is, a castle in the air, Spain being the region of romance.

See also: Chateaubriand

References in classic literature ?
The prize-story experience had seemed to open a way which might, after long traveling and much uphill work, lead to this delightful chateau en Espagne.
1840; "Le Culte du Feu," a folio volume of ponderous research into the religion and ritual of the old Persian Ghebers, published in 1841; "La Soiree du Chateau en Espagne," 1 tom.
Le Grand Casablanca qu'imagine Khalid Safir en 2020 n'est pas un chateau en Espagne.