Real Alcázar de Sevilla
The Palace of Dorne — Water Gardens and the Throne Room
This is where Ellaria Sand and Oberyn Martell walked. The Alcázar's Water Gardens are the heart of Dorne — gardens, fountains and tiled walls that in the series' editing look like an entirely different kingdom. What nobody warns you about is that the real impact of the Alcázar goes far beyond the two minutes it appears in the show: it is one of those places where you spend twice as long as planned because every courtyard is different from the last. The Grotesque Gallery and the arches of the Maidens' Courtyard are the most directly recognisable spaces.
The HBO crew filmed at the Alcázar across several non-consecutive seasons. For season 7, temporary structures were installed in the Gardens to visually extend the space: part of what you see did not exist in the real building.