Faron also, 1660 feet high, with its magnificent precipices of salmon- coloured limestone, commanding both the harbour of Toulon and the Bay of Hyères, is capped with fortifications and pierced with batteries, casemates, and chambers for military stores, a position made by Nature and utilised with supreme skill. Nor must the chain of rock-forts of Campi delle Alte and of Mont Agel above Monaco, dominating the Corniche road be forgotten, ready to drop bombs amidst an army from Italy venturing along that splendid road, nor must Besançon be forgotten, occupying its inaccessible rock--inaccessible that is, to an enemy. "Oppidum maximum Sequanorum," as Caesar described it in his day; "natura loci sic muniebatur ut magnam ad ducendum bellum daret facultatem." Ehrenbreitstein faces the opening of the Moselle into the Rhine; and Frankenfeste holds the key of the Brennerpass; and Dover Castle commands the strait at its narrowest. Königstein crowning a precipitous rock 748 feet above the Elbe, though in Saxony is garrisoned by Prussians, guards the pass down the river from Bohemia; and Peterwardein is a rock-built fortress, that has been called the Ehrenbreitstein and Gibraltar of the Danube. What are these frontier fortresses but the same on an extensive scale as the Gué du Loir, the Roche Corail, and the Rochebrune? In the Middle Ages every city, every little town had to have its outposts and watch-tower on the look-out for the enemy, and to break the first impetus of an attack. But now it is not the town but the nation that has to gird itself about with frontier fortresses. CHAPTER VII SUBTERRANEAN CHURCHES When the periods of persecution of the early Christians had come to an end, and they were able in security to assemble for worship, two distinct types of Church contested for the supremacy--the Basilican and the Catacumbal.