Surrounded by buildings with wide porches of nineteenth-century style, the Square was built by Gaetano Koch shortly after the transfer of the Capital of Italy from Florence to Rome (1871). In Umberto style, it is the largest square in Rome. At its core, it was born spontaneously since the nineteenth century a large outdoor market, which was rebuilt in the 80s as indoor market called "Nuovo Mercato Esquilino". The Square is occupied by a garden, in which are the remains of the Alexander's Nympheus and the so-called "Magic Door", the entrance to Villa Palombara, residence of the alchemist Massimiliano Palombara.