Pope Sixtus IV della Rovere, who served as pope from 1471 to 1481, is credited with ordering the construction of the Ponte Sisto, a new bridge to replace the old Roman crossing over the Tiber River. His ambitious building projects also included the famous Sistine Chapel and the Ospedale di Santo Spirito.
With so many large projects underway, financial resources soon ran low. To raise funds needed for the construction of Ponte Sisto, Pope Sixtus IV introduced a special tax on prostitution. The money collected through this tax went directly toward building the bridge, an example of the unique methods used to support major works in Rome during the Renaissance period.
Source - https://en.wikipedia.org/wiki/Ponte_Sisto