This article argues that the proper study of Roman architecture is hampered by poor plans and the poor literacy of scholars in using plans. The problem is especially acute for the late antique period. In order to illustrate this, a case study of the Column of Constantine is considered, within the uncertain topographical context of Constantinople. There then follows an exposition of experimental work using laser scanning, which seeks to establish a number of simple methods by which new, more accurate plans can be rapidly produced. These new records can also provide important new information pertinent to the structural and decorative histories of Roman buildings, and the street systems in which they are set. Republican, early imperial and late antique structures from Pompeii and Ostia are examined.