Awfully fancy — just for an elevator lobby...
Here's my take.
The entire site (what's above ground and below) is a temple to Osiris/Nimrod (and, ultimately, Satan) and their entire "religion."
It is laid out very precisely according to occult rules of worship and incantation. Everything is a symbol.
The dome itself is a symbol of pregnant womb of Isis, wife of Osiris, or Semiramis, wife of Nimrod (same goddess).
Given the existence of a dome, there should be an obelisk in a circle somewhere on the island which serves as the phallic symbol for Osiris/Nimrod. The correct placement for an obelisk would be at that sundial or compass at the center of the island.
An example of the dome/obelisk combination is the Freemason layout of Washington DC, with the Washington monument positioned directly in front of the Capitol Dome and at the exact center of the Mall.
As you probably know, Nimrod/Osiris are presumably the sons of the fallen angels or of Satan himself.
In the eyes of Satanists, the occult is the world's oldest "religion"...going back to Sumeria and Nimrod and the Tower of Babel after the flood. And in antediluvian times going back to the fall of the "sons of God" who mated with human women (see Genesis 6).