Flea Bottom

Flea Bottom is the poor quarter or district of King's Landing, located on the western side of Rhaenys's Hill. It is a maze-like warren of narrow streets, ramshackle buildings and dark alleys.

Season 1
Arya Stark takes refuge in Flea Bottom after fleeing the Red Keep.

Season 2
Ros identifies Armeca as being from Flea Bottom, but likes to pretend she is from more exotic climes.

In the books
In the Song of Ice and Fire novels, Flea Bottom was the home of the famous knight, Ser Duncan the Tall, who ended up as Lord Commander of the Kingsguard. Survival on the streets of Flea Bottom is tough and hardening. The district is full of tanneries, cheap brothels, low-class inns and pigsties.