But to ascend the Aventine would take us out of our course.  Pushing on to the farther end of the Circus, where the chariots turned at the metae, we may pause a moment, for in front of us is a gate in the city wall, the Porta Capena, by which most travellers from the south, using the via Appia or the via Latina, would enter the city.[23] Outside the wall there was then a small temple of Mars, from which the procession of the Equites started each year on the Ides of Quinctilis (July) on its way to the Capitol, by the same route that we are about to take.  We shall also be following the steps of Cicero on the happy day September 4, 57 B.C., when he returned from exile.  “On my arrival at the Porta Capena,” he writes to Atticus, “the steps of the temples were already crowded from top to bottom by the populace; they showed their congratulations by the loudest applause, and similar crowds and applause followed me right up to the Capitol, and in the Forum and on the Capitol itself there was again a wonderful throng” (ad Att. iv. 1).

We are now, as the map will show, at the south-eastern angle of the Palatine, of which, in fact, we are making the circuit;[24] a and here we turn sharp to the left, by what is now the via di San Gregorio, along a narrow valley or dip between the Palatine and Caelian hills—­the latter the first we have met of the “hills” which are not isolated, but spurs of the plain of the Campagna.  The Caelian need not detain us; it was thickly populated towards the end of the Republican period, but was not a very fashionable quarter, nor one of the chief haunts of social life.  It held many of those large lodging-houses (insulae) of which we shall hear more in the next chapter; one of these stood so high that it interfered with the view of the augur taking the auspices on the Capitol, and was ordered to be pulled down.[25] Going straight on reach the north-eastern angle of the Palatine, where now stands the arch of Constantine, with the Colosseum beyond it, and turning once more to the left, we begin to ascend a gentle slope which will take us to a ridge between the Palatine and the Esquiline[26]—­another of the spurs of the plain beyond—­known by the name of the Velia.  And now we are approaching the real heart of the city.

At this point starts the Sacra via,[27] so called because it is the way to the most sacred spots of the ancient Roman city,—­the temples of Vesta and the Penates, and the Regia, once the dwelling of the Rex, now of the Pontifex Maximus; and it will lead us, in a walk of about eight hundred yards, through the Forum to the Capitol.  It varied in breadth, and took by no means a straight course, and later on was crowded, cramped, and deflected by numerous temples and other buildings; but as yet, so far as we can guess, it was fairly free and open.  We follow it and ascend the slope till we come to a point known as the summa sacra via, just where the arch of Titus now stands, and where then was the temple of Jupiter Stator, and where also a shrine of the public Penates and another of the Lares (of which no trace is now left) warn us that we are close on the penetralia of the Roman State.  Here a way to the left leads up to the Palatine the residence then of many of the leading men of Rome, Cicero being one of them.