Windsor Castle is a royal residence at Windsor in the English county of Berkshire. The castle is notable for its long association with the British royal family and for its architecture. The original castle was built in the 11th century after the Norman invasion by William the Conqueror. Since the time of Henry I, it has been used by succeeding monarchs and it is the longest-occupied palace in Europe.
The castle's lavish, early 19th-century State Apartments are architecturally significant, described by art historian Hugh Roberts as "a superb and unrivalled sequence of rooms widely regarded as the finest and most complete expression of later Georgian taste". The castle includes the 15th-century St George's Chapel, considered by historian John Robinson to be "one of the supreme achievements of English Perpendicular Gothic" design.
Originally designed to protect Norman dominance around the outskirts of London, and to oversee a strategically important part of the River Thames, Windsor Castle was built as a motte and bailey, with three wards surrounding a central mound. Gradually replaced with stone fortifications, the castle withstood a prolonged siege during the First Barons' War at the start of the 13th century.
Windsor Castle occupies a large site of more than thirteen acres (five hectares), and combines the features of a fortification, a palace, and a small town. The present-day castle was created during a sequence of phased building projects, culminating in the reconstruction work after a fire in 1992. It is in essence a Georgian and Victorian design based on a medieval structure, with Gothic features reinvented in a modern style.
Windsor Castle's position on top of steep ground has meant that the castle's gardens are limited in scale. The castle gardens stretch east from the Upper Ward across a 20th-century terrace. Windsor Castle is surrounded by extensive parkland. The immediate area stretching to the east of the castle is a 19th-century creation known as the Home Park. The Home Park includes parkland and two working farms, along with many estate cottages mainly occupied by employees and the Frogmore estate.
The Home Park adjoins the northern edge of the more extensive Windsor Great Park, occupying some 4,800 acres (1,900 ha) and including some of the oldest broadleaved woodlands in Europe. In the Home Park, to the north of the castle, stands a private school, St George's, which provides choristers to the chapel. Eton College is located within about half a mile of the castle, across the River Thames.