If Gibraltar were merely a rock in the ocean, like the Peak of Teneriffe, its solitary grandeur would excite a feeling of awe, and voyagers up and down the Mediterranean would turn to this Pillar of Hercules as the great feature of the Spanish coast, a "Pillar" poised between sea and sky, with its head in the clouds and its base deep in the mighty waters. But Gibraltar is at the same time the strongest fortress in the world, and the interest of every visitor is to see its defences, in which the natural strength of the position has been multiplied by all the resources of modern warfare. A glance at the map will show what is to be defended. The Rock is nearly three miles long, with a breadth of half to three quarters of a mile, so that the whole circuit is about seven miles. But not all this requires to be defended, for on the eastern side the cliff is so tremendous that there is no possibility of scaling it. It is fearful to stand on the brow and look down to where the waves are dashing more than a thousand feet below. The only approach must be by land from the north, or from the sea on the western side. As the latter lies along the bay, and is at the lowest level, it is the most exposed to attack. Here lies the town, which could easily be approached by an enemy if it were not for its artificial defences. These consist mainly of what is called the Line-Wall, a tremendous mass of masonry two miles long, relieved here and there by projecting bastions, with guns turned right and left, so as to sweep the face of the wall, if an enemy were to attempt to carry it by storm. Indeed the line defended is more than two miles long, if we follow it in its ins and outs; where the New Mole reaches out its long arm into the bay, with a line of guns on either side; followed by a re-entering curve round Rosia Bay, the little basin whose waters are so deep and still, that it is a quiet haven for unlading ships, but where an enemy would find himself in the centre of a circle of fire under which nothing could live; and if we include the batteries still farther southward, that are carried beyond Europa Point, until the last gun is planted under the eastern cliff, which is itself a defence of nature that needs no help from man. [Illustration: THE NEW MOLE AND ROSIA BAY.]