Presidio Los Adaes (16NA16), located in present day northwest Louisiana, served as the capital of Spanish Texas for much of the 18th century. Maps and historical documents provide architectural plans for the fort and other buildings on the site but differ in the size and location of several buildings. In 2009, a geophysical survey of the site with ground penetrating radar, magnetometry, electrical resistance, and electromagnetic induction showed good preservation of architectural foundations. Visual assessment of the maps and geophysical data, information from archaeological excavations, and spatial statistics suggests that the fort was originally built as specified by the architect, but over time changed as the needs of the settlement evolved and the population dwindled.