Think that's water in the river? Blood and silver are what flows through Markarth, friend.'
If the Forsworn don't get you, the guards will throw you in Cidhna Mine to work your fingers off. When the guards make an arrest, they check with them first.' They have a whole mine filled with prisoners to dig up silver ore, gets smelted by workers they pay, and they own half the city. It's right there in the name of the most powerful family in Markarth.