Both the Italy and Holland squads have visited the memorial at the former Nazi concentration camp Auschwitz today.
Italy defender Giorgio Chiellini told Gazzetta dello Sport: "For us it has been a very moving experience.
"It was important to come here to remember and to listen to the testimonies of those that survived. We are aware that all that happened here should never take place again."
The Italians travelled from their base in Krakow to visit the memorial.
"It is a day that leaves you shaken," added midfielder Riccardo Montolivo. "You feel a great void. We had to come here."
The Dutch are also staying in Polish city Krakow, where England are due to arrive this afternoon, and Spurs playmaker Rafael van der Vaart tweeted: "We visited Auschwitz with the team today. Unbelievable, this is something I will never forget."
Newcastle United stopper Tim Krul also described the experience on Twitter, saying: "Just visited #Auschwitz with the team. Absolute Madness what has happened there! Can't actually believe it has happened."
Italy are in Group C and take on defending champions Spain in their opener on Sunday, while Holland face Denmark in their first match on Saturday.
