Another major hit in the underground history of the city are the sewers. After Middle Ages, were dictated by authorities to dig septics in every house to dispose the “human nature dirt”. But given that the drinkable water was obtained by numerous wells around the city, this solution, having in mind the soil filtration, was the origin of really violent diseases.
Around 1860, a big plan to transform the city to the actual distribution was being developed. It was called the Plan Cerdá. Not so famous, but in parallel to this plan, Pere Garcia Faria came with a plan not a point less ambitious: create a sewers system to avoid the, from time to time, cholera outbreaks that was decimating the population.
Nowaday, this is the spinal cord of the modern sewers system, a real hit in foreseeing engeenering.
But you don’t have to believe me, you can visit the sewers system. There are guided tours, you can book HERE, but you must accept and follow some instructions: nobody under 8 yo, fully dressed (all body covered in cloth or leather… this mean: no t-shirts, short pants or flip-flops), you need permission of the mayor hall to take pics (so ask for it before the visit), and groups from 10 to 15 members.