Heidelberg Castle is a stunning example of Renaissance architecture, situated in the city of Heidelberg, Germany. Perched on the Königstuhl hillside, it offers breathtaking views of the Neckar River and the Old Town. The castle is a significant historical site, partly in ruins, with sections dating back to the 13th century. It is known for its remarkable architecture and the Heidelberg Tun, the world's largest wine barrel.