Crusaders' Square is located inside Stratholme's Scarlet Crusade side, west from the Market Row. It is the location of the Scarlet Bastion, and is also where adventurers have to do battle against Timmy the Cruel. Numerous members of the Crimson Legion attempt to defend their holdings here, behind crates and rubble.
In the Culling of Stratholme
Crusaders' Square in Old Stratholme can be found west from Market Row. Talking to Arthas for the final time will begin the fight with Mal'Ganis. When defeated, the Dark Runed Chest will appear, as will Chromie.
Crusaders' Square as seen in Old Stratholme.
Beta version of Crusaders' Square in the Culling of Stratholme, showing it pristine.