Regent Street, after we leave Downing, will soon bring us again to the Church of Our Lady, so that we have now completed our circuit of Cambridge. There remain, however, a few outlying spots worth a visit should time serve. Nearest and most picturesque of these is Coe Fen, a long strip of common, lying along the eastern bank of the river, before it enters on its course through the Backs. The best time to see it is at sunset, and the best way to gain it is by following down the narrow byway beside Little St. Mary's, and turning to the left at the bottom. We shall then find ourselves on the Fen, beneath the old wall of Peterhouse deerpark, a delicious, heavily-buttressed, mass of red brick-work, leaning over and curved with age, patched and re-patched all over with all kinds of fragments, giving colour effects that are quite charming.[119] Passing beyond its shelter, and that of its continuing hedge (which divides us from Peterhouse and other gardens), we may take the first turn to the left, up a narrow (and often dirty) byway, which will lead us past the Leys School, the great Wesleyan educational outpost of Cambridge, into the Trumpington Road, where it joins Lensfield Road at Hobson's Conduit. Or, instead of turning to the left we may turn to the right, and, crossing the Cam by the iron footbridge, make our way over "Sheep's Green," the Common east of the river, to Newnham Mill and the Backs. Or we may hold straight on, by the footpath that runs the whole length of the Fen, which will bring us out on the Trumpington Road just by the first milestone, where that road crosses "Vicar's Brook." [Footnote 119: See p. 5.] It is from this side that we notice how this is no ordinary milestone, but a grand monolith twelve or fifteen feet in length, and feel that it must have a story. And so indeed it has, for it is the very first milestone ever set up in Britain since the days of the Roman dominion here. In those days every great road in the country had its series of milestones recording the distance from the central milestone in London, which still exists, in its decay, as "London Stone." But after the mighty organisation of the Roman Empire lost its hold upon the land, roads went to ruin, and milestones were broken up or used for Anglo-Saxon gate-posts. Not till 1729 was the idea of restoring the system entertained; and it was a Cambridge College, Trinity Hall, that first took it up, and carried it out on the road from Cambridge to London. Hence it is that these milestones bear the Crescent of the College shield. And for their inaugural milestone was chosen this grand monolith, which was itself an old Roman milestone.