The last primeval lowland forest in Europe straddles Belarus and Poland, and in it walks the European bison, the continent’s heaviest land animal, which went EXTINCT in the wild in 1927 and was brought back from 54 zoo animals, every living wild bison descending from a dozen of them. The forest was a royal hunting reserve for six centuries, which is exactly why it survived. A UNESCO World Heritage site you can walk into.
Belovezhskaya Pushcha (Belarus)
See it on the map