both originally open to the roof and surrounded by a gallery built into the wall – and St John's Chapel in the south-east. The top floor was added in the 15th century, along with the present roof.[13][17] St John's Chapel was not part of the White Tower's original design, as the apsidal projection was built after the basement walls.[15] Due to changes in function and design since the tower's construction, except for the chapel little is left of the original interior.[18] The chapel's current bare and unadorned appearance is reminiscent of how it would have been in the Norman period. In the 13th century, during Henry III's reign, the chapel was decorated with such ornamentation as a gold-painted cross, and stained glass windows that depicted the Virgin Mary and the Holy Trinity.