Barcelona is one of the best places in Spain for one to be during the observance of remarkable festivals. The celebration of Corpus Christi, which commences on the 30th, is said to be conducted here on a most magnificent scale. Of this I can form some conception from the brilliant procession which I witnessed yesterday afternoon, it being Trinity Sunday. The procession was preceded by two men on mules, over whose necks were strung a pair of tambours, (a kind of drum,) upon which the men were vigorously beating. Then came a priest, bearing a large and elaborately worked cross; after him came the body of the procession in regular order, consisting of young priests in white gowns, chanting as they marched; citizens in black, with white waistcoats and without hats; little girls representing the angels, in snowy gauze dresses with flowers, garlands, and a light azure scarf flowing from their heads; numerous bands of music, some of them playing solemn airs, others quick-steps and polkas; a fine display of infantry, and after all a noble body of cavalry, on fine horses, in striking uniform, each of them carrying a spear-topped banner in their hands. The general appearance of this procession, (each member of which, with the exception of the soldiers, carried a lighted candle or torch in his hand,) marching through one of the superb but narrow streets, while from almost every balcony was suspended a gay "trede," (a scarf-like awning,) either of blue, or crimson, or yellow, the balconies themselves being crowded with clusters of bright-eyed girls,--constituted one of the most brilliant and attractive spectacles that I ever witnessed. Yet they tell me that the procession of Corpus Christi will be infinitely more splendid and elaborate.