The word 'Kraków' originates from 'Krak,' or 'Krakus' - the fabled ruler of the Vistulan tribes. According to various legends (and there are many), Krakus founded the city sometime around 700AD, built Wawel Castle, and vanquished the menacing Wawel Dragon that lived beneath it. King Krak also allegedly beat back the armies of the Roman Empire, and his daughter Wanda (who ruled the city after his death) famously fended off the Germans after they invaded in retaliation for her refusal to marry a German prince. Though scientific evidence of either is otherwise scant, both rulers have prehistoric earthwork burial mounds in the districts of Podgórze (Krakus Mound) and Nowa Huta (Wanda's Mound), respectively. Extensive (though incomplete) inter-war excavations of Krakus Mound failed to produce the mythical king’s remains, however artefacts dating to the 8th century were revealed. Theories vary on the exact age of either mound, but experts agree that they are the oldest man-made structures in Kraków.