Buda Castle of Hungary was also called Royal Palace.
Royal Buda Castle in Budapest - Hungarian Royal Palace. - YouTube (https://www.youtube.com/watch?v=64Paog8HwwY)
The foundation stone of the palace was laid on May 13, 1749, which was the birthday of Empress Maria Theresa of Austria, Queen of Hungary.
The first royal residence on the Castle Hill was built by King Bela IV of Hungary between 1247 and 1265.
Sigismund was King of Hungry from 1387 to 1437. He was also Holy Roman Emperor. He chose Buda Castle as his main residence.