Where is Ravenna?

In Central Italy.  It is the capital of a province of the same name; it is an ancient town, and the see of an archbishop.

     See, the seat of episcopal power; the diocese of a bishop.

     Episcopal, belonging to a bishop.

     Archbishop, the presiding bishop of a province.

[Illustration:  THE GRAND CANAL, VENICE, ITALY.]

What was the origin of the city of Venice?

In the Adriatic Sea were a great number of marshy islands, separated only by narrow channels, but well screened and almost inaccessible, inhabited by a few fishermen.  To these islands the people of Veneti (a part of Italy, situated along the coasts of the gulf,) retired when Alaric, King of the Goths, ravaged Italy.  These new Islanders, little imagining that this was to be their fixed residence, did not, at first, think of forming themselves into one community, but each of the 72 islands continued a long while under its respective masters, and formed a distinct commonwealth.

     Adriatic Sea, a name given to the Gulf of Venice.

     Commonwealth, a republic, a government in which the
     supreme power is lodged in the people.

What circumstance caused them to unite?

Their commerce becoming considerable enough to awaken the jealousy of their neighbors, they united in a body for their mutual protection:  this union, first begun in the 6th century and completed in the 8th, laid the foundation of the future grandeur of the state of Venice.  From the time of this union, fleets of their merchantmen sailed to all the ports of the Mediterranean; and afterwards to those of Egypt, particularly to Cairo, a new city, built by the Saracen princes, on the banks of the Nile, where they traded for spices, &c.  The Venetians continued to increase their trade by sea and their conquests on land till 1508, when a number of jealous princes conspired against them to their ruin; which was the more easily effected in consequence of their East Indian commerce, of which the Portuguese and French had each obtained a share.

     Conspired, united together in a plot.

What is the signification of Mediterranean?

Inclosed within land, or remote from the ocean.  It is more particularly used to signify the sea which flows between Europe and Africa.

Had not Venice a formidable rival in a neighboring republic?

Genoa, which had applied itself to navigation at the same time with Venice, and with equal success, was long its dangerous rival, disputed with it the empire of the sea, and shared with it the trade of Egypt, and other parts, both of the East and West.  Jealousy soon broke out; and, the two republics coming to blows, there was almost continual war between them for three centuries:  at length, towards the end of the 14th century, the strife was ended by the fatal battle of Chioza; the Genoese, who till then had usually the advantage, lost all, and the Venetians, almost become desperate, at one decisive blow, beyond all expectation, secured the empire of the sea and their superiority in commerce.