"Ye thought the orbital penitentiary around Venus was hard ta endure? That place is a vacation spot compared to Davy's Lockdown! If the guard borgs can't find an excuse ta peel the skin off yer bones and the inmates don't use ya for their bettin pool, the pressures o' bein that far beneath the waves will drive ya to the brink, mark my words!"
An underwater prison with a dark past, suitable for any sci-fi, neo-dystopian, or cyber punk setting.
"...the city was built on many levels, linked by stone bridges. But with the improvements in diet and corresponding increase in stature and strength of the populace, these bridges became too low, and the people would hit their heads. The bridges were eventually done away with in 1764, but the scars on the walls where they once jutted out remain, and in Low Bridge Street there is still one extant bridge, measuring about 6' high." - Chronicler Rasill, Mondopedia, Vol II (The Lands of Hyellia)