The Roman History · Amm. 22.16.7

But the greatest of all the cities is Alexandria, ennobled by many circumstances, and especially by the grandeur of its great founder, and the skill of its architect Dinocrates, who, when he was laying the foundation of its extensive and beautiful walls, for want of mortar, which could not be procured at the moment, is said to have marked out its outline with flour; an incident which foreshowed that the city should hereafter abound in supplies of provisions.

Ammianus Marcellinus · translated by C. D. Yonge · 1911 reprint
C. D. Yonge translation (preface dated February 1862); G. Bell and Sons, 1911; Project Gutenberg #28587
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