The lapidarium represents the collection of stone monuments and fragments of archaeological interest to be exhibited in one place. Rome, the eternal city, is characterised by the segmentation of layers and has witnessed its share of destruction and steady reconstruction through its ancient history. In contrast to the historic centre of monuments and the medieval urban fabric, the city contains vast industrial areas in its outskirts such as the former Italgas area of the gasometer in Ostiense. The Tiber river comes as the origin of Rome while the settlement developed on the hills faced the ford along the island.

Next to being in charge of the natural flow of information, goods and cultures over time, the water has inevitably been collecting materials in its embankments, unintentionally exposed through its pure passive storage lacking too much of public attention. This role of both activating urban transformation processes and natural erosion qualifies the river as a source for findings, waste and hidden treasures. Through the exposition of findings from the water, the original gas purification facilities were reused for the sake of a cleaner river: the water itself, its sediments and potential objects were caught by the cranes on the north side of the plot and processed further to synchronise the production of coal and gas.

The flooding provided a sustainable treatment of the structure and at the same time automatically builds up a catalogue of material serving for an eventual exhibition space. The strategy of the main intervention for the masterplan followed the logic of this sequence, proposing an open bath inside the first gasometer where the water–analogous to the gas–was the purest and could be used ideally for the purpose of a new therme. The interpretation was based on the idea of understanding the public behaviour of the ancient Roman bath by analysing and directly translating the order of spaces for individual bodily needs. For the final design of the building, the (idealised) plans of historic examples were turned into the section of the new programme, changing the logic from a horizontal succession of patterns towards a vertical circulation surrounded by the rough texture of the industrial heritage.