In 39, Caligula performed a spectacular stunt by ordering a temporary floating bridge to be built using ships as pontoons, stretching for over two miles from the resort of Baiae to the neighbouring port of Puteoli. It was said that the bridge was to rival the Persian king Xerxes' pontoon bridge crossing of the Hellespont. Caligula, who could not swim, then proceeded to ride his favourite horse Incitatus across, wearing the breastplate of Alexander the Great. This act was in defiance of a prediction by Tiberius's soothsayer Thrasyllus of Mendes that Caligula had "no more chance of becoming emperor than of riding a horse across the Bay of Baiae".