Towering Holes

I DO not know what to make of this, but I thought it well worth taking a photo.

Tower Of London with the Walkie-Talkie Tower looming in the background

I was standing on Tower Bridge, so the picture shows what appear to be recently excavated holes in what is now the base of an approximately southeast-facing wall.

But the filled-in moat no doubt gives a false impression - the holes are presumably some feet above what would have been the surface of the water when the moat was being used for defensive purposes.