Belsay comprises three distinct but related elements: a medieval castle that was enlarged in the early 17th century, a Greek Revival mansion built as a family residence at the beginning of the 19th century, and an outstanding garden linking the two buildings.
The great tower that still dominates the castle was in the 14th century is one of the best-surviving examples of a pele tower – a regional type of fortification built by rich families in the late Middle Ages.