In his essay, The Acquisition of Pienza 1459-1464 , Nicholas Adams examined the various notarial instruments now lodged in the State Archives in Siena and traced the various land purchases by Pius and others in the development of Pienza.
The article is in the Journal of the Society of Architectural Historians, Vol. 44, No. 2 (May, 1985), pp. 99-110. It can be found in http://links.jstor.org/about/asIII.list.html
The abstract of the article is as follows:
"The transformation of the central Italian village of Corsignano into Pienza (1459-1464) by Pope Pius II (Enea Silvio Piccolomini) required an elaborate series of property purchases. Through the discovery of hitherto unpublished notarial memoranda from the Archivio di Stato, Siena, it is now possible to consider the process of urbanization as a distinct series of phases rather than simply as the result of papal will. These documents, recording the price paid for the property, its appurtenances, and the zone of the village in which it was located, reveal that the Pope developed different areas in sequence. Purchasers with a variety of relations to him and the Piccolomini family tended to buy in different areas. With these documents it is possible to begin to consider the Pope's intentions at each stage. It is also possible to use the documents to reconsider some traditional ownership attributions."