With their trunks all bent the northward, these trees look like something straight out of one of the more uncomfortable fairy tales. Surrounded by a larger forest of straight growing pine trees near Gryfino, north-west Poland, this grove of curved trees - dubbed the 'Crooked Forest' - is a mystery. The curved pines, of which there are about 400, were planted around 1930. They were allowed to grow for seven to ten years before being held down in what is thought to have been some kind of human mechanical intervention. Speculation as to what the trees may have been intended for ranges from use in making bent-wood furniture, the ribs for boat hulls or yokes for ox-drawn plows. However, before they could be harvested, the outbreak of the Second World War interrupted the plans of whoever was growing and tending the grove, leaving their plans a mystery.