The house was well oriented to view, ventilation, and dominant location. The veranda, which afforded communication from one part to another out-of-doors, as well as a place to sit, was exposed to the prevailing southwesterly summer winds. In the winter it was equally well placed so as to be in the lee of northeast storms sweeping down the Potomac. The view, hidden today by trees, included Accokeek Creek and a lengthy vista up Potomac Creek. Presumably, a road or driveway skirted the kitchen at the west and perhaps ended in a driveway in front of the house. The gate in Wall E south of the kitchen would have been a normal entrance for horses and vehicles.
Within the garden was the summerhouse built by Mercer in 1765. From the east windows and steps of the house and from the garden could be seen the Potomac, curving towards the bay, and the flailing "drivers" of the windmill near the Potomac shore.
The excavated and written records of Marlborough are a microcosm of Virginia colonial history. They depict the emergence of central authority in the 17th century in the establishment of the port town as a device to diversify the economy and control the collecting of duties. In the failure of the town, they demonstrate also the failure of colonial government to overcome the tyranny of tobacco and the restrictive policies of the mother country. They go on to show in great detail the emergence in the 18th century of a familiar American theme--the self-directed rise of an individual from obscure beginnings to high professional rank, social leadership, personal wealth, and cultural influence. They demonstrate in Mercer's career the inherent defects of the tobacco economy as indebtedness mounted and economic strains stiffened. In Mercer's concern with the Ohio Company and westward expansion they reflect a colony-wide trend as population increased and the need grew for more arable land and areas in which to invest and escape from economic limitations. They show that the war with the French inevitably ensued, with its demands on income and manpower, while following this came the enforcement of trade laws and the immediate irritants which led to rebellion. So Marlborough gives a sharp reflection of Virginia's history prior to the Revolution. It was touched by most of what was typical and significant in the period, yet in its own details it was unique and individual. In this seeming anomaly Marlborough is a true illustration of its age, when men like Mercer were strong individuals but at the same time typifying and expressing the milieu in which they lived.