This imposing building is one of the best preserved ones of the Villa, and is located in a secluded position between the Hall with Doric Pillars and the Winter Palace. Ancient sources give scarce information about it since no sculptures, marbles or other precious objects have been found here.

The name is imaginary, it was created in the twentieth century by Lugli because its plan is similar to that of the Firemen's Headquarters at Ostia. After a series of devastating fires, buildings were built in Roman cities for the firemen; something like this must have existed at Villa Adriana too.

The main entrance leads into a large central courtyard onto which various rooms arranged on several floors open. The high walls still have many travertine blocks which supported the wooden mezzanines of the various floors; the cross vaults collapsed.
There were galleries overlooking the central courtyard and there were wooden stairs that went up to the upper floors.

The structure is similar to that of the rooms of the Hundred Chambers (Cento Camerelle) or the Praetorium Substructures which had the same wooden mezzanines supported by travertine shelves, and were intended to house the slaves serving the Villa.
On the rear side of the building there is a room that served as a guardhouse and gave access to a multiple latrine preceded by a room for the keeper of the same, the latrinarius.

The Firemen's Headquarters had pavements of simple white mosaic without decorations or in opus spicatum (bricks arranged in a fishbone pattern); the walls were plastered. The modesty of the decoration and the multi-seater latrine proved that it belonged to service quarters of the Villa.
There are several hypotheses about it function: barracks for the Praetorians or housing for slaves; or a warehouse for foodstuffs and perhaps for the kitchens that served the nearby Triclinia of the Imperial Palace and of the Golden Square (Piazza d’Oro).