Follow drinking water, sewage, electricity, refrigerated goods, and cargo through the systems working behind the street.
Each treatment step removes a different kind of risk; and no single step does every job
The cheapest mover is a carefully maintained downhill path; until terrain forces a lift
The decisive invention wasn't one pipe but two flows that stopped meeting
The city receives a continuous negotiation among distant supply, local wires, and changing demand
A refrigerated product carries its entire temperature history, not just the reading at arrival
The container mattered because ships, cranes, trains, trucks, corners, and records agreed around it