Just a bunch of random thoughts on the nature of the Dragonpit:
The thick walls of the Pit have numerous rooms and chambers to store saddles, whips, and so on. Dragonkeepers and the rider assigned to the Dragonpit in the event of an attack on the city have small apartments set in the walls, with a view of the Pit floor.
The dragonkeepers have strict protocols for moving dragons, and even princes have to be accounted for when a dragon is loosed for feeding time or to clean their lairs. Usually any Pit visitors are required to remain in the stone benches high above the Pit floor.
The floor's sand layer is often blackened and turned to glass in places from dragonfire. Animal bones and dragon waste is carted off daily. It is not a task that is ever slacked off on, because the dragons are symbols of Targaryen power and must be kept in immaculate conditions.
Because it was made and designed by Free Cities architects, it has a distinctive aesthetic compared to the rest of King's Landing. More like a giant temple than a stable, very flowing carvings in the walls for adornment. Loads of dragon motifs.
The stony walls are often blackened by dragonflame, and the dome is crusted with ash and smoky residue, obscuring the flying dragons carved into it.
The walls have windows, tall and narrow ones that let in bars of sunlight and make the Pit feel less oppressive than it is.
It's BIG. The Dragonpit is the single biggest structure in Westeros aside from the Rock and Harrenhal. It's the first landmark that ships or dragonriders can make out when approaching the city. Inside, it makes Balerion look undersized. It's almost like Erebor from the Hobbit films, just completely absurdly voluminous.
The dragon lairs are also huge, two hundred feet tall at the apex of the arched ceiling, a hundred feet wide, and black with ash. Most of the lairs went unused, as there was forty chambers and only ever about twenty dragons in total- and no more than fifteen or so ever nested under its roof at one time in Targaryen history. The lairs have a half dozen chains for each dragon, with links as big as a man for the adults, and links as big as a human skull for the small ones.
The dragonriders never left through the Main Gate. They always departed and landed at the entrance to each dragon's lair.
The lair entrances are flanked by huge dragon statues, which stood guard over huge signal braziers to denote which lair the dragons should land at. Dragonkeepers would use banners to wave in returning Targaryens.
Pit dragons seldom laid eggs compared to the Dragonmont-dwelling beasts, but any eggs that were produced would be stored in special furnaces or moved to Dragonstone for storage.
