And now look directly north, about eight miles, and you see--no, you cannot see a solitary pillar standing on the open and deserted plain. There is not even a vestige of a ruin near it; and yet there stood in ancient times the great and the learned, as well as the splendid, city of Heliopolis, or “The City of the Sun.” It was of vast extent, and had many large temples; among them one dedicated to the sun, with a mirror so disposed as, during the whole day, to reflect the rays of that luminary into the body of the edifice. Thither came the scholars of ancient times to drink from the streams of knowledge; there Herodotus acquired his lore; and, above all, there Plato studied; and there, too, it is supposed that Moses “was taught in all the learning of the Egyptians.” But neither grandeur nor knowledge itself could avail to save it; and of its many splendid structures, but a single column remains to mark its site. But here at our feet is Cairo, teeming with life, and with the human passions all at work; and yet it seems like a city of the dead. We hear no sound, no cry; life seems to be stagnant there; but it is not. The surface is not greatly ruffled, but beneath it the passions are fermenting: who shall follow them in their various changes and their devious windings? But we will not philosophise. Here, just below us, is the mosque of Sultan Hassan; and, as our time is short, we will hasten to occupy ourselves with its singular history; a history that has a strong dash of the Arabian Nights, and yet is solemn truth, that may be told in open day. This is the largest, and in its architecture the most imposing mosque in Cairo. It is massy, and ornamented with heavy mouldings; and though of the Saracenic style, is a solid and substantial building. And now for its history.