Public domain image hosted by Wikipedia.
That is John Evelyn’s proposed plan for rebuilding London after the Great Fire of 1666. See anything familiar about it? It leapt right out at me, possibly thanks to the context in which it was referenced at Yog-Sothoth.com. Consider now this image, rotated to aid comparison:
Graphic by Eliyak, made public domain.
That’s right, Evelyn based his street layout on the kabbalah’s Tree of Life. My innate knowledge of London is sufficiently weak that I can’t line up locations with any confidence beyond St. Paul’s Cathedral, which is kindly marked on the details for Evelyn’s plan as location 8, meaning it corresponds with the sephiroth of Yesod, associated with Foundation, the moon and “the role of collecting and balancing the different and opposing energies of Hod and Netzach, and also from Tiphereth above it, storing and distributing it throughout the world. It is likened to the ‘engine-room’ of creation.”
As Wren’s St. Paul’s was to be the centerpiece of the new London, perhaps St. Paul’s was to become the threshold between realms, as well as an “engine-room” receiving energy from the other places of power in Evelyn’s plan. To power what? Otherworldly portals? Memetic stabilizers to help London keep its conceptual shape and power?
In our history, Evelyn’s proposed layout for London never came to fruition. The rebuilt streets followed much the same lines as their predecessors and the general configuration survives today. Christopher Wren still had a hand in redesigning many other churches around London, in addition to St. Paul’s and infused them with plenty of mystic symbolism.
 From Wikipedia’s article on Yesod.
 Alan Moore’s graphic novel From Hell contains a chapter which is, essentially, a tour of Wren’s churches that dissects the Masonic elements of his designs and — I think — some of the significance of their locations around London.