Between 1926 and 1929, the third floor was added during the term of President Plutarco Elías Calles by Alberto J. Pani, an engineer and then finance minister and designed by Augusto Petriccioli. Merlons were placed on the towers and parapet and decorative caps were placed on all three doors. The Dolores Bell was placed in a niche flanked by atlantes above the balcony above the central door. The façade was covered with red tezontle stone and installed stone frames on the doors, windows, cornices, and parapets. In the interior, a grand staircase of marble was installed in the central patio (where Diego Rivera would later paint The History of Mexico mural) and constructed stairs to the internal revenue department and the offices of the General Treasury in the north wing. The old Chamber of Deputies, abandoned after a fire in 1872, was reconstructed and re-inaugurated as a museum to the centennial. A statue of Benito Juárez was placed in the north wing near his old quarters. This statue was made with bronze from the cannons of the Conservative Army during the Reform War and from French projectiles from the Battle of Puebla. This caused the Palace to lose its Baroque (and French) appearance and give it the appearance it has today.