"These _Thermæ_ of Caracalla, which were one mile in circumference, and open at stated hours for the indiscriminate service of the senators and the people, contained above sixteen hundred seats of marble. The walls of the lofty apartments were covered with curious mosaics that imitated the art of the pencil in elegance of design and in the variety of their colours. The Egyptian granite was beautifully encrusted with the precious green marble of Numidia. The perpetual stream of hot water was poured into the capacious basons through so many wide mouths of bright and massy silver; and the meanest Roman could purchase, with a small copper coin, the daily enjoyment of a scene of pomp and luxury which might excite the envy of the kings of Asia. From these stately palaces issued forth a swarm of dirty and ragged plebeians, without shoes and without mantle; who loitered away whole days in the street or Forum, to hear news and to hold disputes; who dissipated, in extravagant gaming, the miserable pittance of their wives and children; and spent the hours of the night in the indulgence of gross and vulgar sensuality."--_Gibbon._ In the first great hall was found, in 1824, the immense mosaic pavement of the pugilists, now in the Lateran museum. Endless works of art have been discovered here from time to time, among them the best of the Farnese collection of statues,--the Bull, the Hercules, and the Flora,--which were dug up in 1534, when Paul III. carried off all the still remaining marble decorations of the baths to use for the Farnese Palace. The last of the pillars to be removed from hence is that which supports the statue of Justice in the Piazza Sta. Trinità at Florence. A winding stair leads to the top of the walls, which are worth ascending, as well for the idea which you there receive of the vast size of the ruins, as for the lovely views of the Campagna, which are obtained between the bushes of lentiscus and phillyrea with which they are fringed. It was seated on these walls that Shelley wrote his "Prometheus Unbound." "This poem was chiefly written upon the mountainous ruins of the baths of Caracalla, among the flowery glades and thickets of odoriferous blossoming trees which are extended in ever-winding labyrinths upon its immense platforms and dizzy arches suspended in the air. The bright blue sky of Rome, and the effect of the vigorous awakening spring in that divinest climate, and the new life with which it drenches the spirits even to intoxication, were the inspiration of the drama."--_Preface to the Prometheus._