Today, the State Rooms are open to the public and managed by the independent charity Historic Royal Palaces, a nonprofit organisation that does not receive public funds. The offices and private accommodation areas of the Palace remain the responsibility of the Royal Household and are maintained by the Royal Household Property Section. The palace also displays many paintings and other objects from the Royal Collection.
Kensington Palace was originally a two-storey Jacobean mansion built by Sir George Coppin in 1605 in the village of Kensington. The mansion was purchased in 1619 by Heneage Finch, 1st Earl of Nottingham and was then known as Nottingham House. Shortly after William and Mary assumed the throne as joint monarchs in 1689, they began searching for a residence better suited for the comfort of the asthmatic William, as Whitehall Palace was too near the River Thames, with its fog and floods, for William's fragile health.
In the summer of 1689, William and Mary bought Nottingham House from Secretary of State Daniel Finch, 2nd Earl of Nottingham for £20,000. They then instructed Sir Christopher Wren, Surveyor of the King's Works to begin an immediate expansion of the house. In order to save time and money, Wren kept the structure intact and added a three-story pavilion at each of the four corners, providing more accommodation for the King and Queen and their attendants. The Queen’s Apartments were in the north-west pavilion and the King’s in the south-east. Wren then re-oriented the house to face west, building north and south wings to flank the approach, made into a proper cour d'honneur that was entered through an archway surmounted by a clock tower. The palace was surrounded by straight cut solitary lawns, and formal stately gardens, laid out with paths and flower beds at right angles, after the Dutch fashion. The royal court took residence in the palace shortly before Christmas 1689, and for the next seventy years, Kensington Palace was the favoured residence of British monarchs, although the official seat of the Court was and remains at St. James's Palace, which has not been the actual royal residence in London since the 17th century.
Additional improvements soon after included Queen Mary's extension of her apartments by building the Queen's Gallery and, after a fire in 1691, the King's Staircase was rebuilt in marble and a Guard Chamber was constructed, facing the foot of the stairs. William had constructed the South Front, to the design of Nicholas Hawksmoor, which included the Kings' Gallery where he hung many works from his picture collection. Mary II died of smallpox in the palace in 1694, and in 1702, William suffered a fall from a horse at Hampton Court and was brought to Kensington Palace, where he died shortly afterwards from pneumonia.
After William III's death, the palace became the residence of Queen Anne. She had Christopher Wren complete the extensions that William and Mary had begun, resulting in the section known as the Queen's Apartments, with the Queen's Entrance, and the plainly decorated Wren designed staircase, that featured shallow steps so that Anne could walk down gracefully. These were primarily used by the Queen to give access between the private apartments and gardens. Queen Anne's most notable contribution to the palace were the gardens. She commissioned the Hawksmoor designed Orangery, modified by John Vanbrugh, that was built for her in 1704. The level of decoration of the interior, including carved detail by Grinling Gibbons, reflects its intended use, not just as a greenhouse, but as a place for entertaining. Also, a magnificent 30 acre (121,000 m2) baroque parterre, with sections of clipped scrolling designs punctuated by trees formally clipped into cones, was laid out by Henry Wise, the royal gardener.