It was founded by the Argentine priest Msgr. José León Gallardo with donations from the Argentine bishops, with the first stone being laid on 9 July 1910, the centenary of Argentine independence. Mrs. Saenz Peña, wife of the
President of Argentina, was present at the ceremony. Construction took twenty years, and the church was finally inaugurated in 1930. From then until 1989, the church was served by
Mercedarian fathers; it is now served by Argentine diocesan clergy from a community in an adjoining house. It was built by the architect Giuseppe Astorri with a 7-storey
campanile and a 2-storey façade in the style of ancient Christian architecture, with a central depiction of the
Lamb and symbols of the four
Evangelists. The interior is also in ancient, Roman-Byzantine style, with a nave and two aisles divided by
Ionic columns, a
Cosmatesque-style pulpit and lectern and a
polychrome marble floor (laid in geometric patterns with the national
coat of arms of Argentina in the centre, and a memorial slab to its founder, which was presented by the Argentine cardinals and bishops at the
Second Vatican Council). In the apse at the east end is a mosaic of Our Lady of Sorrows by
Giambattista Conti and a
high altar decorated with onyx and covered by a
baldachino supported by four granite
Corinthian columns. The choir is separated from the nave by an altar ring of white marble which includes
intaglia and bronze gates with the national coat-of-arms and the arms of the Order of the
Mercedarians. At one altar is a small statue of
Our Lady of Luján, principal patron of Argentina. Since 1967, it was a Cardinal's Titular Church. ==Special festivals and Masses==