The house ranks architecturally with many of the great mansions built in the late Colonial period; however, it is the only house directly inspired from a plate in Palladio’s, I Quattro Libri dell’Architettura. It is arguably the most exquisite house remaining from the Colonial period in America.
Architect William Buckland cleverly adapted Palladio's Villa Pisani design to satisfy the tastes of colonial Annapolis. He re-designed the plan to accommodate the tastes for asymmetrical regional preferences and modified the hyphens from Palladio's arched entries to more practical single storey connecting links. He also incorporated fashionable urban design by sinking the windows in the method mandated by the London Building Act of 1774. This device provided better protection from fire and gave the overall design a greater degree of visual solidity and three dimensionality (see image at right). This adaptation from Palladio's model marks his maturity as an architect and ranks him as one of America's first and finest architects.
The initial design of Thomas Jefferson’s Monticello was taken from the Villa Cornaro in Piombino Dese, Italy, in Book II, Chapter XV of I Quattro Libri dell’Architettura, but this façade was later covered up by Jefferson’s own expansions to his house. Thomas Jefferson made two drawings of the Hammond-Harwood House when he served the government in Annapolis in 1783-4. One could assume that Jefferson recognized the house as derived from Palladio because his knowledge of The Four Books of Architecture was extensive. He referred to the book as his architectural “bible” and the plate of the Villa Cornaro follows the Villa Pisani plate; and directly opposite the Villa Cornaro in some 18th century English transcriptions of the work.