It’s a royal surprise!

Kate Middleton and Prince William headed to Cardiff Castle in Wales as part of the festivities for Queen Elizabeth II‘s Platinum Jubilee and brought along two special guests—Prince George, 8, and Princess Charlotte, 7, the eldest of their three children.

The family all greeted well-wishers who lined up to see them, including performers and crew members involved in the special Platinum Jubilee Celebration Concert taking place in the castle grounds that day. During their trip, the Duke and Duchess of Cambridge and their kids checked out the show’s music setup backstage.

Charlotte wore a navy wool coat dress and Mary Janes, while George and William sported navy suits and Kate was dressed in a red wool coat dress and black stiletto pumps.

The family’s visit to Cardiff Castle comes two days after all the Cambridges, including youngest son Prince Louis, 4, joined the Queen and other royals on a Buckingham Palace balcony to watch the Trooping the Color parade.