Located on the western bank of the river Rhine, Rheinfels Castle is a castle ruin offering spectacular views of the river and its surrounding areas in Sankt Goar, Germany. This massive castle was once known to be the largest fortress in the Middle Rhine Valley. Today, it is the largest castle overlooking the river Rhine. Majorly occupied by castle ruins, few outer buildings of this complex are now restored as a luxury hotel, wellness center, and a restaurant. Visitors can also see some better-preserved structures in the museum at this historic place.