Prince William and his wife Duchess Catherine arrived in Warsaw, Poland, on Monday with their two children Prince George and Princess Charlotte. The royal family is currently on a five-day tour of Poland and Germany.

William, who is third in line for the British crown, and his family visited a former concentration camp and met with Holocaust survivors as part of their trip. The Duke and Duchess described the visit as “shattering” and as a “terrible reminder of the cost of war,” according to the BBC.

The couple also left a heartfelt note in the visitors log book at the site which read, “We were intensely moved by our visit to Stufhof, which has been the scene of so much terrible pain, suffering and death. All of us have an overwhelming responsibility to make sure that we learn the lessons and that the horror of what happened is never forgotten and never repeated.”

 

Later this week, the family will head to Germany for a meeting with German Chancellor Angela Merkel. Afterwards, they are scheduled to visit Berlin’s Holocaust museum and memorial.

William and Kate will also participate in a boat race. William will cox one boat while Kate will cox the other.