In fact, Metropolitan Stephen had already established his residence here in 1661. In 1925, when the Romanian Orthodox Church was elevated to the rank of Patriarchate, the Metropolitan Residence became the Patriarchal Residence and the Metropolitan Cathedral became the Patriarchal Cathedral, provisionally, until a new, suitable cathedral was built.

In the course of time, the Cathedral and the Palace with its chapel were repaired, extensions and transformations were made, the most important works of which took place between 1792-1799 (initiated by the Metropolitan Pilaret II and Dositei Filitti), 1834-1839 (initiated by Metropolitan Gregory IV Dascălul and completed after his death), 1932-1935 (initiated by Patriarch Miron Cristea), 1960-1962 (initiated by Patriarch Justinian Marina, designer arch. Paul E. Miclescu), in 1989 and 2000-2001, with the blessing of the venerable Patriarch Theoctist, and in 2008, under the guidance of His Beatitude Patriarch Daniel.

The cathedral regained its original form following restoration work carried out between 1960-1962 on the initiative of Patriarch Justinian Marina. It was built on the architectural model of the church of Curtea de Argeș Monastery, built by Neagoe Basarab. Like the latter, it is composed of an altar and nave, with a trefoiled plan, a raised pronaos supported on octagonal stone columns, with remarkable capitals carved in a composite and polished manner at the top, and four prismatic spires at the elevation.

On the outside, the facades of the cathedral are delimited all around in two registers by a quasi-median stone belt. The monument in Bucharest, however, is larger than its model in Curtea de Argeș. In the porch, above the entrance door, is the feast day icon of Holy Sovereigns Constantine and Helen, painted in 1665. The present neo-Byzantine mural was painted by Dimitrie Belizarie between 1932-1935, replacing the neoclassical mural by Nicolae Polcovnicul from 1834-1839 (which was also superimposed on an older layer of painting). The royal icons of the temple were enamelled by Otilia Oteteleșanu between 1961-1964 in the Patriarchal workshops.

The relics of Saint Dimitrie the New, placed in a beautiful silver reliquary, were brought to the cathedral from the village of Basarabi, on the right bank of the Danube, on 13 July 1774, by Metropolitan Grigorie II (1760-1787). Saint Demetrius the New is the spiritual patron saint of Bucharest, and his feast day, 27 October, is every year the occasion of a great pilgrimage of the faithful from all over the country. To the right of the pronaos are the tombs of the patriarchs of the Romanian Orthodox Church: Miron Cristea († 1939), Nicodim Munteanu († 1948), Justin Moisescu († 1986) and Teoctist Arăpașu († 2007). The tomb of the third patriarch of the Romanian Orthodox Church, Justinian Marina († 1977), is in the ‘Holy Trinity’ church of the Radu Vodă Monastery in Bucharest, the chapel of the Orthodox Theological High School Seminary ‘Metropolitan Nifon’ in Bucharest.

To the east of the cathedral’s altar is the belfry built by the voivode Constantin Brâncoveanu in 1698 and restored in 1956-1958, as well as the round column with inscriptions in memory of the metropolitans Teodosie († 1708) and Ștefan II († 1738), whose tombs were originally located on this site.