The Shieldhall is an old feast hall of dark stone at Castle Black.
In years past, when the Night's Watch was much larger in number, the Shieldhall's walls had been hung with rows of brightly colored wooden shields. When a knight took the black, his shield would adorn its wall and he would take up the plain black shield of the brotherhood. When a knight died, his shield was removed so it could go to the deceased's pyre or tomb. As the Night's Watch declined in number, however, the noble brothers dined instead with the smallfolk in the common hall. The dark Shieldhall was used infrequently, as it was difficult to heat, infested with rats, and had worm-eaten wooden rafters.
A Dance with Dragons
After letting Tormund's free folk through the Wall, Lord Commander Jon Snow has them gather with the Night's Watch within the Shieldhall, as it seats two hundred and has the capacity for another hundred. Jon notices fewer than a dozen shields along its wall.
Hundreds of knights meant hundreds of shields. Hawks and eagles, dragons and griffins, suns and stags, wolves and wyverns, manticores, bulls, trees and flowers, harps, spears, crabs and krakens, red lions and golden lions and chequy lions, owls, lambs, maids and mermen, stallions, stars, buckets and buckles, flayed men and hanged men and burning men, axes, longswords, turtles, unicorns, bears, quills, spiders and snakes and scorpions, and a hundred other heraldic charges had adorned the Shieldhall walls, blazoned in more colors than any rainbow ever dreamed off.—Thoughts of Jon Snow