The Palace of the Grand Master of the Knights of Rhodes, also known as the Kastello or Castello, is a medieval castle located in the Old Town of Rhodes, Greece. It was built in the 14th century by the Knights Hospitaller, who ruled Rhodes at the time, and served as their headquarters and a fortress to protect the island from attacks.

The palace was largely destroyed by an explosion in 1856 and then reconstructed by the Italians in the early 20th century. Today, it serves as a museum that showcases artifacts and exhibits from the island's long and fascinating history. Visitors can explore the restored rooms, see examples of medieval art and architecture, and learn about the many different civilizations that have influenced Rhodes over the centuries.

The palace's architecture reflects the influences of both the Knights' medieval Gothic style and the Renaissance style of the Italian architects who reconstructed it. The building is a stunning example of the fusion of different cultural and artistic traditions, with intricate stone carvings, frescoes, and other decorative elements adorning its walls and ceilings.

The palace is surrounded by a moat and fortified walls that provide a glimpse into the past and highlight the strategic importance of the fortress in its time. Visitors can climb to the top of the ramparts for a panoramic view of the Old Town and the harbor.

The Palace of the Grand Master of the Knights of Rhodes is a UNESCO World Heritage Site and a must-see attraction for anyone interested in history, architecture, and art.