this, scarcely a break in the line of dazzling shops, until we reach the vicinity of Union Square, a pretty oval park, with a noble fountain in the midst, and lofty and handsome houses all round, situated on perhaps the highest ground on this part of the island. Half a mile beyond is Madison Square, a green expanse, about which wealthy citizens are now building elegant residences of brown freestone, with some attempt at architectural display. Near this, still northward, is the lower or distributing reservoir of the Croton Aqueduct, standing on high ground, and looking something like a fortress--no great ornament, perhaps, but an object of much interest. Fifth Avenue, on the west of Broadway, stretching north from Washington Square--an inclosure of about ten acres, well planted with elms and maples--it is the Belgravia of New-York--in the estimation of those who inhabit it; a paradise of marble, upholstery and cabinet work, at least; not much dignified, as yet, by works of high art, though the region boasts a few specimens, ancient and modern; but in luxury and extravagance emulating the repudiated aristocracy of the old world. This is, and is to be, a street of palaces and churches throughout its whole extent, always provided that the changeful current of Fashion do not set in some other direction too soon, carrying with it all the _millionaires_ that are yet to arise within the century. In that event, the costly mansions of Fifth Avenue will inevitably become hotels and boarding-houses,--a reverse which so many grandly intended houses of elder New-York have already experienced.