Caerphilly Castle is a 13th-century fortress in Caerphilly, Wales, built by Gilbert de Clare, a Norman lord. The castle features a unique water-based defense system, with a large lake and moat surrounding the castle. Its impressive architecture includes a large gatehouse, curtain walls, and several towers, including the impressive South East Tower. The castle has undergone several restorations and renovations over the centuries, and today it stands as a testament to medieval engineering and architecture. Visitors can explore the castle's grand halls, towers, and battlements, and enjoy the scenic surroundings of the lake and surrounding countryside.