What are ancient German stoves made of?

Ancient German stoves, often known as "Kachelöfen," were traditionally made from ceramic tiles, which were both functional and decorative. These stoves featured a firebox lined with firebrick or clay and were designed to efficiently radiate heat throughout a room. The exterior was typically adorned with colorful glazed tiles, showcasing intricate designs that reflected local artistry. Additionally, some stoves incorporated metal components, such as cast iron, to enhance durability and heat retention.