Karl met Princess Marie Louise of Bulgaria in Madrid, where she was living with her mother. She was the only daughter of Boris III of Bulgaria by his wife Princess Giovanna of Italy. Karl announced his engagement to Marie Louise in December 1956. They married in a quiet civil ceremony in Amorbach on 14 February 1957. Amorbach had been the residence of the House of Leiningen since 1803, and the town's streets were lined with hundreds of cheering spectators; Karl's family owns huge estates in South Germany, and was considered to be one of the wealthiest of Germany's noble families. As of 1957, his family's fortune was valued at $1.5 billion. The couple also married in a Greek Orthodox religious ceremony in Cannes on 20 February 1957.