The Aachen Cathedral, also known as the Imperial Cathedral, is a significant historical and architectural monument located in Aachen, Germany. It was built in the 8th century as the palace chapel of Charlemagne, the first Holy Roman Emperor, and was expanded over the centuries. The cathedral is considered one of the most important examples of early medieval architecture and is a UNESCO World Heritage Site. It is renowned for its impressive Carolingian architecture and its beautiful interior, which features a blend of Roman, Byzantine, and Germanic styles. The cathedral houses Charlemagne's Palatine Chapel, which is a masterpiece of early medieval architecture and one of the best-preserved examples of its kind in the world. The Aachen Cathedral is also home to several important religious relics, including the original crucifix of Charlemagne and the Holy Robe, which is believed to be the seamless garment of Jesus.