When Silesia fell to Bohemia in the 14th century, King Kazimierz III Wielki fortified the frontier by building a chain of castles from Kraków to Częstochowa. This 100km stretch comprises the Kraków−Częstochowa Upland.
The plan worked and the Bohemians were never able to penetrate the wall. Centuries later, in 1655, however, the Swedes invaded and destroyed many castles. More turbulence in the 18th century completed the process, leaving impressive ruins for the 21st-century traveller.
The Upland region is also known as the Jura, having been formed from limestone in the Jurassic period some 150 million years ago. Erosion left hundreds of caves and oddly shaped rock formations, which can still be enjoyed in the Ojców National Park.
An excellent way to explore the Upland is by hiking the Trail of the Eagles’ Nest (Szlak Orlich Gniazd), which winds 164km from Kraków to Częstochowa. Tourist offices in Kraków and Częstochowa can provide information.