That the Pfalzgrafenstein once was part of one of the most profitable customs posts on the Rhine is evident from its location:
Standing in the middle of the river, the fortress is only accessible by ferry. In 1327, the Pfalzgraf and later Emperor Ludwig IV erected a five-sided keep on the small Rhine island as the first part of the fortification - much to the dismay of the bishops of the time and even the Pope, who were concerned about the church's lucrative dominance in collecting tolls. With the construction of the ring wall and walkways starting in 1340, the resilience of Pfalzgrafenstein was significantly increased. In 1504, it even survived a 39-day siege during the Bavarian-Palatinate War of Succession unscathed.
Undoubtedly, "the Pfalz" is now one of the most photographed motifs in the Middle Rhine Valley.

A small passenger ferry brings visitors from Kaub dry-footed onto the "stone ship." The sailing times can be found on the website of the General Directorate of Cultural Heritage: https://tor-zum-welterbe.de/pfalzgrafenstein