In addition to large stable fortifications made of stone or bricks that are listed as national heritage sites, the Czech Republic is home to debris of dozens of smaller field fortifications from early modern times. They are mostly relics of battles and military campaigns associated with the Thirty Years' War in 1618-1648, a series of shorter wars during the 18th century and the Napoleonic Wars.
So far, only sites from the Thirty Years' War have been systematically studied and documented, i.e., a total of thirty fortifications found in seven localities.