This is the Palacio Nacional de Queluz, halfway between Lisbon and Sintra. It was home to the Portugese Royal Family from about 1750 to 1850 and is known locally as the Portugese Versailles.
For some reason it is not on the tourist trail, gets little publicity and very few people go there.
We only went because we were chatting to an Uber driver and he mentioned it.
Fabulous place,