While Eighth avenue is the principal avenue for business purposes, Fifth avenue is distinguished for the splendor of its private residences, to which, with the exception of a few magnificent churches and institutions, it is entirely devoted. It begins at Washington square, near the centre of the city, and extends northward in a perfectly straight line for six miles, and is pre-eminently the street of palaces. The buildings are large, constructed of marble, or of the several varieties of free-stone, the fronts ornamented with cornices, entablatures, porticos, and columns, elegantly carved and sculptured. Everything is massive and expensive, and the surrounding streets so far partake of its magnificence that one may travel miles amid unbroken lines of palatial splendor. Here dwell the millionaires who control so largely the shipping, the railroad, the banking, and the legislative interests of the country. Much unoccupied space still remains on this peerless avenue for wealth and genius to lavish their dazzling inventions. For the relief of Broadway, Laurens street is now being widened and made to connect Fifth avenue with West Broadway. This opens another general thoroughfare for uptown travel, and will probably attract its share of business firms. It will greatly disturb the quiet and, mar the beauty of the lower portion of this brilliant avenue, and already a number of its palaces, near Union square, have been converted into business houses.