Elztal is home of four castles: K?chlinsburg, Kyffelburg, Schwarzenburg, and the most famous Kastelburg built in 1260. The term Castle is most often applied to a self-contained fortress. Castles were also developed to defend key part of the countryside such as a Waldkirch mountain pass or river estuary and often exploited the natural geography to support the defensive walls through exploitation of cliffs, rivers, hills etc. The adoption of the concentric system, improved during the 13th and 14th centuries, had a solid defence, by the massive strength of the concentric castle and in some cases, by natural inaccessibility. Its final fall was due to the introduction of gunpowder as a propellant. In the 14th century the change begins, in the 15th it is fully developed, in the 16th the feudal system has become an anachronism.

     Castles were built not only as a defensive measure from hostile enemies, but as an offensive weapon. During the Middle Ages kings often built castles for offensive reasons: a castle was a stronghold from which a lord or baron could control surrounding territory.