Can we kind of, sort of get serious and think about Babylon, Egypt, Spinx and Pyramids.
1. It is possible as Egypt to build either Pyramids or Sphinx. And only with careful micromanagement.
2. Since UHV asks for Pyramids only (not for both because of #1) what is the point of Sphinx (former Stonehenge, if someone remembers) , with it's current effect and name?
Sphinx will always end up in Babylon with human Egypt. And human player will never use Sphinx-Pyramid synergy, which was in mind when designing those wonder effects.
Obviously in ideal world one has to build Sphinx first and use it's effect to build Pyramid. But because Thebes still have Fledging culture they cannot build another wonder for few more turns. Even if Babylon was going for Spinx they can now switch to Pyramids and finish it. So this entire design succeeds in only frustrating poor human player and offers neither synergy nor excitement in finding ways to beat Babylon. One simply can't. And Babylon ends up with unhistorical Wonder and will have less room for historical wonders such as Gardens and Ishtar.
Solution:
Any Wonder except Moai Statues and Sphinx can be only built in the city with 100+ culture (on top of the existing rules). This will require Pyramids to need Sphinx's culture. It's only logical -- Sphinx and Pyramids got to be together like love and marriage. Offers interesting micromanagement options for human Egypt. But still Sphinx does not guarantee Pyramids, because if human player is too slow on higher difficulties Babylon can still reach to 100

with palace and ziggurat and build Pyramids super fast.
Or simply swap Sphinx with new wonder, like
Black Obelisk with no Stone bonus which grants free barrack in every city and fair game for any civ that manages to build it (even China). It will create more excitement than current Sphinx.