Hiram Gillett built this three-storey block on land purchased from Robert N. Waddell in 1844. In 1876, Gillett sold the block to Stanley Paterson, Secretary and Treasurer for the Midland Loan and Savings Company who established a stock exchange in the block. Prior to completion of the Town Hall in 1853, the first Town Council met in Gillett's Block.

In the late 1980’s the windows on the two main streets were replaced with modern glass, retaining the wooden sashes, the cost being assisted by a provincial grant of $85,000.  In 2017, the building was sold, and this owner has applied to replace all, but the two curved windows, with new vinyl windows. Heritage Committee and Planning staff recommended against this replacement.

Council, after hearing the owner’s appeal, returned the matter of retention of heritage windows, with apparently greater costs, for further study. "Upon receipt of a policy document to provide an assessment approach for the designated district, and continued rejection of the owner’s request, Council took no action on the report, ignored the municipal easement that had been registered on the property as a result of the public moneys that had assisted the previous work, and voted to grant the owner his request to install the vinyl replacements."

There is great concern that this exception may now become the custom.  In the past decade ACO Port Hope has helped defray the additional estimated costs of repairing wooden windows and brick for several owners in the downtown Heritage District.