Eastern Europe's northern countries - the Baltic nations - all have special Christmas and Christmas Eve traditions that probably stem from pagan seasonal rituals. While some traditions, like the hay that is brought into the house to represent Christ's manger, have been Christianized to the point that their pagan roots may seem non-existent, other traditions have undeniable pre-Christian origins.
Prognostications, superstitions, and the belief that the dead will come back to eat the Christmas Eve leftovers, as is common on Lithuanian Christmas Eve, are almost certainly remnants of pagan Eastern Europe. Estonians still refer to the Christmas season as "Yuletide," which predates Christmas as we know it today. And the legend of Riga and the first Christmas tree? Probably another tradition that has been taken from the Yuletide practice of burning trees that has been adapted to Christianity.