Wawel Hill was an ideal strategic point. The natural elevation above the river amidst marshland meant that people first appeared on the hill tens of thousands of years ago. The first buildings were probably erected here even before the establishment of the Polish state. Some have linked the etymologies of the name Wawel to a ravine, a limestone ravine, but the word wawel could also mean a lofty place among marshes and swamps. There were quite a few hypotheses. The hill built of limestone, with its caves, was an ideal place to erect buildings that were probably the seat of power for the Vistula tribe.  In the 10th century, a stone palatium –the duke's palace – stood on the hill. Churches were also erected on Wawel Hill. The cathedral was built after the creation of the Bishopric of Kraków in 1000. When Wawel Hill became the seat of the princes in the 11th century, Wawel buildings, both secular and sacred, were extended in successive styles: Romanesque, Gothic, and Renaissance. However, the Italian architect Bartolomeo Berecci turned the former palace into an impressive castle complete with a courtyard. Wawel Castle had its royal gardens and vineyard, which is being restored today. After the relocation of the royal residence to Warsaw and the Swedish invasions, the golden development of Wawel Hill came to an end. At the turn of the 19th and 20th centuries, the significant restoration of Wawel began. Today it is a landmark of Kraków and one of the most recognisable places in the world.