The Robert Taylor Co. Building is one of no less than 17 four story buildings, all Italianate in design and essentially all, if not all, designed by architect William Thomas. Each of the 17 buildings in question is now a City of Halifax Registered Heritage Property. The entire block was built between 1859 and 1863.
Notwithstanding the above, heritage plaques, as well as other sources, give wildly different dates of construction for the buildings in this block. For example, the Halifax Heritage Properties List gives a date of 1869 for the Robert Taylor Co. Building, while the plaque on the building is also dated circa 1869. I consider the Dictionary of Architects in Canada page for William Thomas to be the closest to correct.
The way was made for the rebuilding of much of downtown Halifax by three major fires between 1857 and 1861 - on New Year's Eve, 1857, September 9, 1859, and January 12, 1861. The September 9, 1859 fire levelled the entire north block of Granville Street, enabling the reconstruction of the entire block simultaneously. As a result a single architect, William Thomas, designed the entire block to be harmonious in design, choosing the Italianate style for the block, freestone and cast iron being prominent throughout. Following the New Year's Eve, 1857 fire new legislation was passed prohibiting large wooden buildings within the developed part of Halifax.
...the Granville Street fire, which wiped out the north block of the street in September 1859, induced the Thomas firm to open a Halifax office. It was first advertised in October 1859 while Thomas was busy preparing unified designs for seven proprietors rebuilding the centre of the city's prosperous dry goods trade. Thomas's individual building designs, unified by massing, height, detailing and materials, created a distinctive streetscape which reflected contemporary mercantile confidence. The cast iron storefronts which Thomas introduced along most of the Granville Street block had not only the well-recognized advantages inherent in the material but also the prestige of manufacture by the leading New York producer of architectural cast iron, Daniel Badger. The buildings popularized the Italianate detailing and forms which would soon dominate prime Halifax building of every type. The Thomas office remained open until 1863 when, with Granville Street rebuilt and a subsequent design for the rebuilding of the Union Bank completed, C.P. Thomas, the resident Thomas partner, left Halifax for Montreal.
From St. Mary's University