From A Wiki of Ice and Fire
The Golden Pit is a fighting pit located in Meereen.
A Dance with Dragons
After Viserion and Rhaegal are unleashed upon the city the ruling council of Meereen fill the Golden Pit with beasts that Hizdahr zo Loraq had gathered for his games to feed the dragons and keep them sated. The dragons however prove to have a taste for mutton and instead keep returning to Daznak's Pit, which is filled with sheep, whenever they grow hungry.