From what I read in Spanish newspapers years ago when I was a teen, Juan Carlos was offered the Royal Palace. Too big, is the largest palace in the world. Also was offered El Pardo Palace but this building was touched by the Franco curse.
The Francos used it as their home since it would be offensive to move the family to the Royal Palace. Franco's wife, a horrible and cruel person whom I recall stories from when I was a kid in the 1960s, said
her family would occupy El Pardo for a thousand years. When King Juan Carlos took over, he evicted all of them and recovered the property to be used as the stay for foreign dignitaries.
He got stuck with the small Zarzuela palace Franco placed him in, and that actually saved his life years later. King Juan Carlos had installed his very own TV station to broadcast emergency messages.
When the Franco army officers invaded the Courts and held elected officials' hostage, they forgot about capturing the King. He turned on his Zarzuela TV station on and ordered them to put their weapons down. And they did.
So that little palace entered history for saving Spain from a coup, or possibly a micro civil war. I left Spain permanently for the USA a few years after, but it was quite an event with democracy saved from the Zarzuela Palace
