The vault by the exit to Arsenalsgatan.
Rumor is that two Italian tiler teams miscounted, that’s why the pattern on the floor doesn’t match up. The artist solved the problem by pouring a barrel of oil over the platform.
Perhaps artist Ulrik Samuelson was inspired by the Tsesis oil spill in 1977, when the Soviet oil tank Tsesis capsized outside Stockholm. About 1000 cubic meters of oil leaked out to sea when the ship was damaged.