This is a row of old Roller Presses machine tools that were powered by steam. They were used for minting silver coins. A Roller Press is used for flattenning bars of metal, which can then be stamped and coined.
It is located in the Casa de la Moneda, the old Spanish mint where the silver from the mines of Potosí was transformed into coins.
The original minting machines are preserved in a near-perfect state. The oldest machines were made of huge wooden gears and powered by slaves or animals (depending on availability). Later they used steam-powered machines, but luckily they kept the old machines untouched (just in case!). This huge building is now a national museum.