She has several.
England:
Wales:
N. Ireland:
In London
The most famous Stone Castle is the White Tower of London (Tower of London)
The castle is officially named Her Majesty's Royal Palace and Fortress, but it is commonly known as The Tower of London. It is located on the north bank of the River Thames in London. The castle was first built in 1078, and it now has over two million visitors per year.
The Tower of London.
The Tower of London.
Windsor Castle and the Tower of London.
Tower of London
The tower of London
the tower of london
Tower of London, Leeds, Edinburgh, Stirling, Warwick, Alnwick
Langley Castle is a medieval Tower House.
the white tower in London happens to be it :)