Future novels set in "historical" (present day) London will have to romanticize this weird combination of architectural approaches.
On the one hand, the stone fortress has stood for longer and against a wider variety of situations, weather, and hordes. On the other hand, I imagine that the Dread Lord of the Wobbly Glass Superstructure has some pretty puissant powers (perhaps blasting lightning bolts from the roof?).
This post's theme word is procumbent, "lying face down; prone; prostrate." or "of a plant: growing along the ground without putting new roots." The Tower of London looks procumbent in the highrise-dotted skyline of the city.