Europe, the Muggle nation of St. Riddle.
It was a Muggle nation made up of several islands, with a population of only a few hundred thousand. The Muggle Riddle family had colonized it during the Age of Discovery. After Voldemort returned, he had claimed ownership of the nation on Azkaban Island. (Chapter 714)
He guided the Pure-blood families and major factions who had pledged their allegiance to him to invest there, drawing the authorities' attention while secretly shifting the focus of development to the Americas and quietly building up a large Squib mercenary force. (Chapter 779)
Later, when the major factions followed Chairman Riddle to the Americas for good, their European assets were almost entirely seized and destroyed by a "furious" Dumbledore and the Ministries of Magic in various countries.
As the various factions divided up the spoils, St. Riddle was intentionally or unintentionally overlooked.
After all, it was the family estate of Voldemort's Muggle father.
Who knew whether Voldemort would take offense?
No one wanted to set foot there, only to end up on the radar of a Dark Lord like him. That would be the most terrifying thing of all.
Well, someone did want it.
Mr. Fudge, the British Minister for Magic, had planned to acquire the magical world's ownership of the land for Anton. Unfortunately, after consulting with Anton, he eventually gave up—Anton had no interest in managing it.
In this world, apart from Anton, who dared to occupy Voldemort's old home, the only other person who could do so was Dumbledore.
Actually, Mr. Grindelwald could have done it too, but decades of imprisonment seemed to have worn down the old wizard's spirit. He no longer paid much attention to affairs in the magical world.
And so, St. Riddle naturally fell into Dumbledore's hands.
Old Dumbledore was