The former Imperial Palace (Kaiserpfalz) in Kaiserslautern was built in around 1152 by Emperor Frederick I Barbarossa. The only remaining parts of the Imperial Palace are a few carved blocks of red sandstone and remnants of the stone outer wall of the double chapel added by Frederick II.
Following the excavation of the rest of the Imperial Palace and the evaluation of the findings, the city mounted the historic foundations. The Domus (imperial building) originally measured 25 by 19 meters and was 19 meters high. In order to get a real sense of the size of the building, a 3D steel and tamped concrete construction that imitates the size and shape of the Imperial Palace was built.
You can see the remains of the castle wall, which have now been fully uncovered, just next to what was the Imperial Palace. The Stapf fortress was also rebuilt in this location. The fortress was erected at the beginning of the Thirty Years’ War, in around 1619/1620, by fortress builder Adam Stapf on the orders of the widow of Frederick IV, Elector Palatine of the Rhine. Stapf built primary defensive walls with trenches, bastions and curtain walls which protected the medieval castle and city walls.
References:The Jan Hus Memorial stands at one end of Old Town Square. The huge monument depicts victorious Hussite warriors and Protestants who were forced into exile 200 years after Hus, and a young mother who symbolises national rebirth. The monument was so large that the sculptor designed and built his own villa and studio where the work could be carried out. It was unveiled in 1915 to commemorate the 500th anniversary of Jan Hus' martyrdom. The memorial was designed by Ladislav Šaloun and paid for solely by public donations.
Born in 1369, Hus became an influential religious thinker, philosopher, and reformer in Prague. He was a key predecessor to the Protestant movement of the sixteenth century. In his works he criticized religious moral decay of the Catholic Church. Accordingly, the Czech patriot Hus believed that mass should be given in the vernacular, or local language, rather than in Latin. He was inspired by the teachings of John Wycliffe.