The dominant feature of the Diez townscape is the high medieval castle. The oldest parts of the structure date from the eleventh century. The castle was abandoned as a residence from the mid-1700s, and from 1743 to 1784, the count's castle was used as a Nassau office building. Subsequently, it served as a prison until 1927.
During World War II, Diez Castle was commandeered by the German Army to interrogate 'prisoners of special interest' captured on the western front, one prisoner being Gertrude Legendre, the female Office of Strategic Services clerk/translator captured in 1944. In the eighteenth and nineteenth centuries, the castle was the site of the largest processing center of Lahn marble.
Since June 2006 it has served as a youth hostel and, since 2007, also contains a museum.
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.