[3] The rione was born after the unification of Italy (such as San Saba, Testaccio and Prati), from the convention, signed in 1886, between the Boncompagni (heirs of the Ludovisi) and the Municipality of Rome.

With this act, the Lords of Piombino assigned to the housing development the area of Villa Ludovisi: about 25 hectares of park between the walls and the historical rioni of Trevi and Colonna, which between the 17th and 19th centuries had extended eastward up to Porta Salaria (the present Piazza Fiume).

The technical and financial arm of the operation (uselessly deprecated by the European intellectuals of the time as an unforgivable ugliness) was the Società Generale Immobiliare, established in Turin in 1862, which followed the movements of the capitals of the Savoy kingdom moving its headquarters first in Florence (in 1862) and then finally in Rome in 1880; here it became, for a century, the great protagonist of the Roman building speculation.

Another season of intense construction took place between 1925 and 1935, with the Hotel Ambasciatori, the INA building and the headquarters of the Ministry of Economic Development (born as Chamber of Fasces and Corporations).

The rione borders with: Gules, three golden bands withdrawn in the head and a gold dragon cut at the tip (coat of arms of the Boncompagni-Ludovisi) family.