According to the cookbook Estonian Taste and Traditions, a kringel is sweetbread made with cardamom or saffron and raisins and twisted into the shape of a pretzel. It's mandatory in Estonia at birthdays, weddings, and other special occasions, which sounds reasonable.
This version of a kringel from Estonian food blog Just Love Cookin takes some liberties with tradition, replacing cardamom and saffron with cinnamon, ignoring the whole raisin thing, and twisting two rolled logs together to form a circle. Check out the recipe, which author Anna Maria Ciolacu has kindly provided in English.
Urgent: Someone please make this with traditional American cinnamon roll dough and report back.