The most characteristic building of the Museum has the shape of a quarter of a circular crown and is called the Roundabout. This unique construction of steam locomotive depots, also called engine-shed and, in some Latin American countries, “round house”, was the heart of its operating system. The historic Vilanova depot has twelve tracks with twelve ditches where the railway operators carry out the different maintenance tasks for the steam locomotives. Currently, the most valued and delicately preserved vehicles from the Museum's collection are exhibited on these tracks.
The railway company MZA, which had its independent operating network in Catalonia (MZA- Red Catalana), built the building following the industrial modernist style of the early 20th century. On the deck there were originally chimneys with round outlets for smoke and steam from the machines, structures that disappeared before the conversion into a Museum. Since its construction in 1919, three important rehabilitation actions have been documented in this building and an integral architectural intervention project is pending.
The functions carried out by the railway workers inside were those of greasing and preparing the locomotives for service, the supply of materials such as coal, grease, sand or water, the cleaning and conservation operations of the different elements, the repair of breakdowns and also the organization of the driving staff to ensure the different services.
Employees of different categories were attached to the depots, although the most numerous were those of traction, machinists and stokers. Up to 900 employees came to work in the Vilanova facilities, in an atmosphere full of smoke, soot and grease that today can be recalled when visiting the old productive facilities.