Various topics studied over a period of years revealed both Jefferson’s intentions and what he actually built. The semi-oval or half-ellipse on the northeast side of the house is one of Monticello’s most prominent landscape features. Historic documents and field surveys showed Jefferson’s close attention to mathematical detail and the probable location of the fence which may relate to an original road alignment. Reverse perspective analysis of old photographs confirmed the location of rows of Mulberry trees he planted at the house. Research also confirmed his desire to build a bridge at Thoroughfare Gap, where the stone arch bridge of the Thomas Jefferson Parkway now stands, and revealed bridges both here and abroad that were admired by him.