The Church of the Sacred Heart, although never completed, is of architectural significance as one of the first and finest full blown red brick Baroque church designs in Victoria, and the second classically styled Catholic church built in Victoria. The interior is of aesthetic significance for exhibiting a richness of interior decoration particularly the paintings by A. F. D Cavallaro (who arrived in Australia from Italy in 1899), and are executed on canvas and then fixed to the elliptical barrel vaulted ceiling. The encaustic tiled floor by the Australian Tessellated Tile Company, stained glass by Hardman of Birmingham, and Brooks Robinson of Melbourne, Stations of the Cross by J Hennessey, and altar decorated by Ferguson, Urie and Lyon are also important elements.
The new church was designed by Tappin Gilbert and Dennehy and constructed in 1897-99 of red brick, with unpainted cement render dressings in the Baroque style. A chapel and large dome were proposed in the original design but never constructed. The altar in the new church was relocated from St Patrick's Cathedral, where it had been originally installed in 1868. In the 1930s and 1940s the Church of the Sacred Heart became a primary focus for Carlton's Italian community, which continued into the 1960s.
Our Lady's Grotto, also known as the Marian Grotto, or the Lourdes Grotto, was erected in the grounds of the church by volunteers in 1941 to the design of the Italian priest of the day Reverend Father Modetti. It is of social significance for its association with Melbourne's Italian community, with construction undertaken as an act of solidarity of the Italian community, at a very difficult time during the Second World War.