Huge water defences were created by damming the local streams, and the resulting fortifications proved able to withstand assaults by land and water in 1266. John of Gaunt spent lavishly in the late 14th century, turning the medieval castle into a palace fortress designed in the latest perpendicular style. The Earl of Leicester then expanded the castle during his tenure in the 16th century, constructing new Tudor buildings and exploiting the medieval heritage of Kenilworth to produce a fashionable Renaissance palace.