Cornwall’s stone post office, on the northwest corner of Pitt and Second Streets, with its tall clock tower was the most photographed feature of early downtown Cornwall. The building was designed by Architect Thomas Fuller and was built between 1882 and 1885 by local contractors Gordon & L.A. Ross at a cost of more than $47,900 ($3+ million in 2024).

In the early 1950s, it took more than 120 blows from a 3,000-pound stone hammer and the repeated tugs of a crane and power shovel to topple the post office and its tower. It was replaced with the Seaway building.