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:Saint-Émilion is a picturesque medieval village renowned for its well-preserved architecture and vineyards. The town and surrounding vineyards was made a UNESCO World Heritage Site in 1999, owing to its long, living history of wine-making, Romanesque churches and ruins stretching all along steep and narrow streets.
An oppidum was built on the hill overlooking the present-day city in Gaulish times, before the regions was annexed by Augustus in 27 BC. The Romans planted vineyards in what was to become Saint-Émilion as early as the 2nd century. In the 4th century, the Latin poet Ausonius lauded the fruit of the bountiful vine.
Because the region was located on the route of the Camino de Santiago, many monasteries and churches were built during the Middle Ages, and in 1199, while under Plantagenet rule, the town was granted full rights.