Pfalzgrafenstein Castle is a historic fortress located on an island in the Rhine River near Kaub, Germany. Built in the 14th century, it served as a toll station for river traffic, allowing the Electorate of the Palatinate to collect fees from passing ships. The castle's strategic position made it an important defensive structure during various conflicts. The castle features a distinctive round tower and thick stone walls, showcasing medieval architecture. Today, Pfalzgrafenstein Castle is a popular tourist attraction, accessible by boat, and offers visitors a glimpse into the region's rich history and scenic views of the surrounding landscape.