Marcello Piacentini was the son of the architect Pio Piacentini.

He studied at the Academy of Fine Arts and at the Faculty of Engineering of the University of Rome.
Piacentini created his own simplified, slightly modernized version of the neoclassical style, fully consistent with the ideology of the Italian Novecento.
One of Piacentini's early buildings is the tower of the National Insurance Institute in Brescia on Piazza della Vittoria.
He designed Italian exhibition pavilions for international exhibitions in Brussels, San Francisco and Paris.
Marcello Piacentini led all projects for the general development of the city of Rome, for example, the construction of the new Via della Conciliazione from Piazza San Pietro to Castel Sant'Angelo.
After World War II, he successfully underwent a formal “purification” procedure (un’effimera epurazione) and worked as a professor of urbanism at the Faculty of Architecture of the Sapienza University of Rome until 1955.
The Sapienza University Library houses the “Piacentini Foundation”: more than two thousand volumes and sixty periodicals donated to the university in the 1970s by the daughter of the outstanding architect Sofia Annesi Piacentini.
The collection of paintings was inherited by the great-grandson of the artist’s best friend, the architect Marcello Piacentini.