If visitors to Egypt's capital have only the time to visit just one mosque, then it should be the Mosque of Ahmed Ibn Tuloun. It is one of the largest mosques in the world and, even today, the grand scale and extreme simplicity of the mosque's courtyard and four covered colonnades are impressive. When it was begun in 876 it was intended to accommodate all of the new city's worshippers for Friday prayers. In the centre of the courtyard is a fountain built in the thirteenth century, which until quite recently was still in use to perform the ablutions before prayer. Below the coffered ceiling of the colonnades, a two kilometre-long frieze made of sycamore-wood and inscribed with one fifteenth of the Holy Qur'an, runs around the whole mosque. If you can manage to climb to the top of the spiral minaret, inspired by the minaret of the mosque in Ahmed Ibn Tuloun's town of Samarra in Iraq, the views of the Citadel and Cairo are spectacular. The mosque of Ibn Tuloun is truly breath-taking. Ahmed Ibn Tuloun had been sent to rule Cairo in the ninth century by the Abbassid Caliph in Baghdad. He managed to build his own new city, moving it away from Al-Fustat to Al-Qitai, nearer the centre of what is modern Cairo, and he even established his own dynasty to govern Egypt. He brought with him the latest ideas from Baghdad and created order in his new capital. His mosque was the crowning glory of the city itself. What wonder it must have inspired in the city's inhabitants to see something so massive as this. How they must have marveled at the power of their new ruler, who could build such a thing so immense. The mosque was entered then, as now, through a ziyada, or enclosure. In other words, beyond the four towering walls of the mosque's courtyard there is another high wall. The space in between runs all around the mosque. This space was later used as a bazaar, with merchants selling every conceivable item to the worshippers as they entered and left the mosque, but it was originally intended to provide space between the place of worship and the hustle and bustle of the street outside. Men and women would walk in from the noise and commotion of the street, passing through the walled enclosure to enter the silence and peace of the mosque. Even today, you get out of your taxi or walk up the street from As-Saliba street and then you leave the noise of Cairo behind as you enter a haven of peace and tranquility. Ingenious in its simplicity, the idea of the ziyada was to help the worshippers to forget the cares and the concerns of daily life and to focus on Allah alone. In the quiet of the mosque, they could fall prostrate before the Lord of Life and beseech Him for help. Nothing remains now of Ahmed Ibn Tuloun's city, except his mosque. The palaces and the storerooms of the city are long gone. The great stables for the army's horses are nowhere to be seen. The men and women who desired to serve their ruler's every need have died long ago. The minaret, inspired by the minaret of Samarra, now serves to remind us only of the tragic days we have all seen in modern Iraq. Kingdoms rise and fall. Nations hold sway over other nations for a short time, believing themselves to be invincible, vying with one another as to who is the greatest. The power of Allah, alone, is constant. We read in the holy Qur'an in Surat Al-A'raf: And every nation has its appointed term; When their term is reached, neither can they delay it Nor can they advance it an hour (or a moment). Holy Qur'an 7:34 The vast throng of worshippers that once used to pray on a Friday is now no longer here, but the mosque of Ahmed Ibn Tuloun still allows people of all religions and of none to take time out from the cares of life and to focus on what is really important to them. The small but faithful congregation may not be huge any more, but the Adhan still calls people from the street outside to pray five times a day in worship of Allah, placing all their trust in Him. Ibn Tuloun's mosque speaks to a changing world about something that never changes. We hear it in the words of the Call to Prayer: Allahu Akbar, God is the Greatest. British Muslim writer, Idris Tawfiq, is a lecturer at Al-Azhar University. The author of eight books about Islam, he divides his time between Egypt and the UK as a speaker, writer and broadcaster. You can visit his website at www.idristawfiq.com.