Pliny the Younger in his letter Ttajan: Sir, the people of Nicomedia spent 3,329,000 sesterces upon an aqueduct, which was left in an unfinished state, and I may say in ruin, and they also levied taxes to the extent of two millions for a second one. This too has been abandoned, and to obtain a water-supply those who have wasted these enormous sums must go to new expense. I have myself visited a splendidly clear spring, from which it seems to me the supply ought to be brought to the town as indeed they tried to do by their first scheme - by an aqueduct of arches, so that it might not be confined only to the low-lying and level parts of the city. Very few of the arches are still standing; some could be built from the shaped blocks {lapis quadratus} which were taken from the earlier work, and part again, in my opinion, should be constructed of brick {opus testaceum}, * which is both cheaper and more easily handled, but the first thing that might be done is for you to send an engineer skilled in such work, or an architect, to prevent a repetition of the former failures. I can at least vouch for this, that such an undertaking would be well worthy of your reign owing to its public utility and its imposing design.
See:
- Pliny the Younger : Letters - BOOK X , 37 Letters http://www.attalus.org/old/pliny10a.html