The Jewel Tower in London is one of only two surviving sections of the medieval royal Palace of Westminster, the other being Westminster Hall. It was built in 1365-1366 to house the private treasures of Edward III and its alternative name was the "King's Privy Wardrobe". In the early 17th-century it became a records office for the House of Lords. From 1869 until 1936 it was the home of the Board's Standards Department. The Jewel Tower is not to be confused with the Jewel House at the Tower of London and is not the home of the Crown Jewels.

The tower is a three-storey building constructed mainly of Kentish Ragstone, and stands across the road from the current Palace of Westminster, home of the British Parliament. It was located at the far southern end of the old palace complex, and was built into the defensive walls but was detached from the main buildings, which explains its survival of the great fire of 1834 which destroyed most of the palace.

The tower sat in a corner of the royal gardens and was protected by high walls and a moat. The unusual L-shape design of the building can be attributed to the fact that King Edward ordered that the tower should not take up any space in his garden. To fulfill this brief the builders were forced to encroach onto land belonging to Westminster Abbey. For this the monks were never properly compensated and they were forced to construct a new wall to mark the boundary between the palace and the abbey. This wall is still standing and now forms part of Westminster School.