Fortifications: Description of Remains
Description of Remains
The city of Sirkap is completely surrounded by a massive fortification wall with numerous defensive bastions. Marshall notes that the thickness of the wall varied between 4.5 and 6.5 meters, and he estimates the height to be between 6 and 9 meters. On the site map produced by Marshall, the fortifications are designed as one irregularly shaped polygon—the north and east sides are quite regular, while the south and west sides are defined in part by the natural contours of the small hills and Tamra Nala river respectively. However, in the more detailed Ghosh map, there is clear evidence of a interior cross-wall. This wall is located at the northern edge of the two hillocks in the southern portion of the enclosure. From west side at the Tamra Nala, Ghosh finds evidence of an actual fortification walls, and further to the east he writes “Cross-Wall (?)”. 
For Marshall’s full account, see Taxila: An Illustrated Account of Archaeological Excavations Carried Out at Taxila under the Orders of the Government of India between the Years 1913 and 1934 (Varanasi: Bhartiya Publishing House, 1951), pp. 113-114.
This wall divides the enclosed territory into a “Lower City” which contains the urban center in a grid-layout, and an “Upper City” which contains two monasteries, a larger structure that is perhaps a Mahal (palace), and a high mound about which Ghosh speculates might have been a Citadel. 
Ahmad Dani, in further surface explorations, confirms both Marshall’s and Ghosh’s accounts of the fortification wall, see The Historic City of Taxila (Tokyo: Unesco, 1986), pp. 91-92.
Further complicating the matter, the fortification wall was not built all at once, but rather, it was strengthened and expanded over at least four centuries, if not more.
See Marshall, Taxila, vol. I: p. 114. Analysis of the masonry types, not only in the various construction phases of the fortification wall but also in the construction phases of stupas and residential walls as well, has become the preferred method of dating the material remains of Sirkap. Two recent revisions of Marshall’s classification and dating of Sirkap’s masonry types can be found in Kurt A Behrendt, The Buddhist Architecture of Gandhara (Leiden: Brill, 2004), pp. 255-268 and T. Fitzsimmons, Stupa Designs at Taxila (Kyoto: Institute for Research in Humanities Kyoto University, 2001), pp. 5-13. Behrendt finds evidence for four types of masonry in his chronological system, whereas Fitzsimmons finds evidence for twelve phases. While Fitzsimmons may be right that there were more than four phases of construction, it is very difficult to distinguish many of his phases, and the Behrendt system seems to be more applicable, although less precise, over all of Sirkap.