The triumphal procession prepared itself on the Campus Martius and entered the city through the Porta Triumphalis, whose location is unfortunately not entirely certain (it was someplace right by the Campus Martius, probably in the Servian wall). Here the triumphator met the senate and the magistrates, and headed towards the Capitoline by means of a rather indirect route that we don't really have good information on. We know that the triumphator stopped at the forum, and he stopped at several temples along the way to sacrifice and make dedications. We also know that the big part of the triumph, which was extremely old, was the procession down the Via Sacra and up the Capitoline, where enemy chiefs were executed and offerings made to the god. Beyond that much of the route is conjecture