William the Conqueror built the White Tower in 1066 as a demonstration of Norman power, siting it strategically on the River Thames to act as both fortress and gateway to the capital. It is the most complete example of an 11th century fortress palace remaining in Europe.

The most famous castle built by William the Conqueror in London is the Tower of London, specifically its central keep known as the White Tower. Construction began around 1078 as a massive stone fortress designed to awe, subdue, and terrify the local Londoners while protecting the city from foreign invaders. Over nearly a thousand years, it has served as a royal palace, a notorious prison, an armory, and a treasury. In 2026, it remains an iconic symbol of British history and a UNESCO World Heritage site. Visitors can explore the 11th-century Chapel of St. John the Evangelist and view the Royal Armouries' vast collections. It is a high-value strategy to take a tour with a Yeoman Warder (Beefeater) to hear the grim and glorious tales of the castle's past. The Tower is not just a building; it is a living monument where the traditions of the "Keys Ceremony" continue every night, just as they have for centuries.