A detailed map of Teotihuacán is being prepared through the use of photogrammetry and ground survey. The city's maximum limits have been circumscribed, and it appears that they surround an area of more than 10 square miles. Part of this area was occupied only during the first phase of the occupation of Teotihuacán (Tzacualli) in the Pre-Classic period; Tzacualli phase Teotihuacán appears to have covered an area of approximately 3 square miles. The maximum area reached by the city during its later phases appears to be close to 9 square miles, but how much of this area was actually occupied during any one period of time remains to be determined. The central 4.5 square miles of the city seem to have been subject to extensive planning (grid pattern, streets, and blocks of uniform size). Teotihuacán appeared as a settlement of great size in the Pre-Classic period and grew to mammoth proportions during the Classic period. No population estimates are yet possible. The Ciudadela now appears to have occupied a central rather than a southerly position in the city. Several Early Classic period Maya pottery fragments were found near the city's eastern border in the immediate vicinity of Tlamimilolpa where similar fragments had previously been found by Linné.