The foundation stone for Holy Trinity Church was laid by Bishop Perry in 1871. The Gothic Revival style church, designed by architect Leonard Terry, was built by Goss and Fleming from 1871-74 to replace an earlier prefabricated building. The intended tower and spire were never added. It is a substantial bluestone building with slate roof comprising a five bay clerestoried nave with aisles, chancel and organ chamber.
The vicarage was built in 1886 to a design by Terry and Oakden. It is a two storeyed, hip-roofed, stuccoed building in a Gothic Revival style with Tudor and Italianate influences. It is surrounded by a mature garden dominated by a large Moreton Bay Fig. The poet and novelist Ada Cambridge lived at the vicarage from 1893 to 1910 with her husband the Rev George Frederick Cross. The timber Sunday School Hall facing Pasco Street was opened by the Archbishop of Melbourne in 1906.
Holy Trinity Church, Vicarage and Hall have architectural, historical and scientific (horticultural) significance to the state of Victoria.
Holy Trinity Church, Vicarage and Hall are architecturally significant as a highly intact ecclesiastical complex set in a picturesque location on Nelson Place. The church is one of the finest examples of the work of the Anglican diocesan architect Leonard Terry. It is significant for its lofty proportions and its five bay clerestoried nave with aisles in the English Gothic Revival manner. The interior features a number of significant fixtures and fittings, including stained glass by Napier Waller and William Montgomery, pipe organ by William Anderson, baptismal font, and the original altar reredos which now forms the entrance screen. The church also contains features with maritime associations including the chancel rails which are from the HMVS Cerberus and brass bell from the pilot vessel HMCS Victoria. The Gothic Revival vicarage, in a rustic garden setting, has considerable architectural significance. Pointed arches and trussed gables and the asymmetrical massing of each gabled bay lend medieval references to the design with Italianate influences evident in the cast-iron verandah.
The vicarage has historical associations with Ada Cambridge, 1844-1926, an important figure in the history of Australian literature. Ada Cambridge grew up in Norfolk, England and in 1870 accompanied her new husband Rev George Frederick Cross to Victoria. They lived in various country parishes before moving to Williamstown in 1893 where they remained until 1910. She was the first significant Australian female poet writing three volumes of poetry and also producing 21 novels, two autobiographies and contributing to journals. She was also the first president of the Women Writers' Club. While living at the vicarage in Williamstown, Ada wrote a number of works including her autobiography Thirty Years in Australia and a companion volume The Retrospect.
The Acacia karroo is of scientific (horticultural) importance as it is rare in cultivation, there being only three other known trees in Victoria.