Between 2004 and 2013, the Belgium international was an Ajax player.
Now 32, Alderweireld said: "The training is very highly regarded worldwide. But it also has to do with the opportunities that youth players get in the first team and the confidence they enjoy.
“I look back on my Ajax time with a fantastic feeling.
"I am privileged to have been able to experience that time, because it gave me the tools for my further career: the foundation and the insights to become a top player. When you are young, you have to work very hard on yourself. And that was perfectly possible at Ajax, because there was every opportunity to improve."
On Ajax's youth system, Alderweireld added: “People are constantly trying to improve to stay the best. Of course I can't judge other academies because I haven't been there. But I wouldn't have wanted anything other than the Ajax training."