Hall of Columns

This large hall takes its name from the numerous pillars of reinforced cement which once supported the three boilers in the Boiler Hall on the floor above. 

Several hoppers are also visible in the ceiling, similar to the truncated-pyramidical funnels, which were filled with the cinders from the coal used to feed the boilers. 
A hatch in the lower part of the hoppers allowed the cinders to be recovered, collected in carts and carried on the communal trucks of the Garden Services to be used in the gardens and parks of Rome for drainage.