Poznań’s Ostrów Tumski – an island embraced by the rivers Warta and its tributary Cybina, the oldest part of Poznań – was described by Pope John Paul II in these words: "Poland began here".[Anna Plenzler; Historic monuments in Poznań; Poznań 2007. This is the place where in the mid-10th century, in place of an earlier settlement, Mieszko I founded a castle. In 968, the first bishopric was established here and soon afterwards the first cathedral was erected – the pre-Romanesque and Romanesque relics of the cathedral can now be viewed in the shrine’s crypt. In the seventh decade of the 10th century, the castle was extended and surrounded with mighty walls, 20 m wide and about 10 m high. Another structure built at approximately the same time was a palatium (palace) the remains of which were discovered in 1999 by archaeologists working under the supervision of Prof. Hanna Kóčka-Krenz from the Institute of Prehistory at Adam Mickiewicz University of Poznań. The whole of Poland heard about Poznań’s Ostrów Tumski at that time. Still, the research goes on. Also the mighty earthworks – unparalleled in Europe – going back to the times of Mieszko and Chrobry, and discovered recently at Posadzego St clearly indicate Poznań’s position at the dawn of history. [Anna Plenzler; Historic monuments in Poznań; Poznań 2007.