The Silesian Ramparts are the longest archaeological site in Poland. This medieval structure is considered the equivalent of the famous Great Wall of China.
These are the until-recently-mysterious Silesian Ramparts, built in the 14th and 15th centuries on the border of the former Duchy of Głogów. The medieval Szprotawa District (districtus sprotaviensis) bordered the Duchy of Żagań to the west and the Duchy of Jawor to the south.
The structure was enormous considering the local conditions. A system of ramparts and ditches was painstakingly constructed over several dozen kilometers, terminating at rivers or marshes. Sometimes the fortifications were so strong that they consisted of up to four adjacent ramparts. Hedges were planted and maintained on their crests to prevent sudden intrusions into the duchy. To give you an idea, at some sites the fortification system was over 40 meters wide with the height of the ramparts being about 2.5 meters!