Nero's Wall

 is a limited-time decoration released on March 17, 2016, as part of the Burns' Casino 2016 Event. It's available for purchase in The Store once the player unlocks Nero's Palace Arch.

Trivia

 * It can be rotated on all 4 directions.
 * Two of them cannot overlap at corners.
 * It shares this distinction with the Biohazard Wall.
 * It is one of only two items affecting righteousness that is not unique.
 * The other one is the Training Wall.