Spire of Skulls
From A Wiki of Ice and Fire
The Spire of Skulls is the name given by the Great Masters of Meereen to a monument located on the market square inside Meereen's great western gate. Ser Barristan Selmy considers the monument to be "ghastly".
The Winds of Winter
This information has thus far been released in a sample chapter for The Winds of Winter, and might therefore not be in finalized form. Keep in mind that the content as described below is still subject to change.