The Nevsky Prospect is the most fashionable thoroughfare and the street devoted to the best shops. It is from two to three hundred feet in width, and extends for a distance of three miles in nearly a straight line to the Alexander Nevsky Monastery, forming all together a magnificent boulevard. On this street may be seen the churches of several dissenting sects, such as Roman Catholics, Protestants, Armenians, and a Mahometan mosque. Hereon also are the Imperial Library, the Alexander Theatre, and the Foreign Office. The metropolitan cathedral of St. Petersburg is also situated upon this main artery of the city, and is called Our Lady of Kazan,--finished with an elegant semi-circular colonnade, curving around a large square much like that of St. Peter's at Rome. This edifice is superb in all its appointments, no expense having been spared in its construction. The aggregate cost was three millions of dollars. One item of costliness was observed in the massive rails of the altar, which are formed of solid silver. The church contains between fifty and sixty granite columns brought from Finland, each one of which is a monolith of forty feet in height, with base and capitol of solid bronze. Why the architect should have designed so small a dome as that which forms the apex of this costly temple with its extended façade, was a question which often occurred to us. Within, upon the altar, is an aureole of silver bearing the name of God, inscribed in precious stones of extraordinary value. The sacred images before which lamps are always burning are literally covered with diamonds, rubies, emeralds, and sapphires. One of the diamonds in the crown of Our Lady of Kazan is of fabulous value, and dazzling to look upon. Within these walls was observed the tomb of Kutuzof, the so-called "Savior of Russia" on the occasion of the French invasion of 1812. Outside, in front of the cathedral, are two admirable statues in bronze standing before the bending corridor of each wing, representing historical characters in Russian story, but whose names are quite unpronounceable in our tongue. The cosmopolitan character of the population of St. Petersburg is indicated by the fact that preaching occurs weekly in twelve different languages in the several churches and chapels of the city.