The bridge of Pera at Constantinople, 40 braccia wide, 70 braccia
high above the water, 600 braccia long; that is 400 over the sea and
200 on the land, thus making its own abutments.

[Footnote: See Pl. CX No. 1. In 1453 by order of Sultan Mohamed II.
the Golden Horn was crossed by a pontoon bridge laid on barrels (see
Joh. Dukas' History of the Byzantine Empire XXXVIII p. 279). --The
biographers of Michelangelo, Vasari as well as Condivi, relate that
at the time when Michelangelo suddenly left Rome, in 1506, he
entertained some intention of going to Constantinople, there to
serve the Sultan, who sought to engage him, by means of certain
Franciscan Monks, for the purpose of constructing a bridge to
connect Constantinople with Pera. See VASARI, _Vite_ (ed. Sansoni
VII, 168): _Michelangelo, veduto questa furia del papa, dubitando di
lui, ebbe, secondo che si dice, voglia di andarsene in
Gostantinopoli a servire il Turco, per mezzo di certi frati di San
Francesco, che desiderava averlo per fare un ponte che passassi da
Gostantinopoli a Pera._ And CONDIVI, _Vita di M. Buonaroti chap._
30_; Michelangelo allora vedendosi condotto a questo, temendo
dell'ira del papa, penso d'andarsene in Levante; massimamente
essendo stato dal Turco ricercato con grandissime promesse per mezzo
di certi frati di San Francesco, per volersene servire in fare un
ponte da Costantinopoli a Pera ed in altri affari._ Leonardo's plan
for this bridge was made in 1502. We may therefore conclude that at
about that time the Sultan Bajazet II. had either announced a
competition in this matter, or that through his agents Leonardo had
first been called upon to carry out the scheme.]

The Euphrates.