Gate of Babylon

The King’s Treasure.
A key-shaped sword that leads to the golden city.
Once the spatial link is established, the tools in the treasury can be freely taken out at will.
Of course, it goes without saying that the more riches the user possesses, the more powerful this Noble Phantasm will be.
The reason it is the only one of Gilgamesh’s Noble Phantasms that has an English name is because “Babylon” has already become synonymous with “the city of evil” and “the golden city.”
It is likely that imitations such as the Road of Babylon also exist.

Fate/side material: Fate Encyclopedia