In 2004 and later in 2005 and 2006, the Montpelier Archaeology Department excavated the footprint of an underground utility bunker that was installed in 2007 for to hold the HVAC and utilities for the restored mansion. These excavations provided important clues to the massive landscaping the mansion grounds underwent in the 1809-1812 building campaign. The deep deposits of clay fill brought into this area were found comingled with architectural rubble dating to the 1809-1812 renovations and provided the clues to associate these two changes to the mansion. Further, the findings at the bunker excavation site provided evidence that corresponded with deposits throughout the mansion grounds that began to hint at the massive landscaping campaign the Madisons enacted during this time period. The discoveries made during these excavations put into focus the scale of investment that Madison made to the landscape surrounding his newly renovated mansion.