The story begins in Ashkelon, on the Mediterranean coast. A shrine to Husayn's head was "rediscovered" there in 1091, at a politically convenient moment: the Fatimid vizier Badr al-Jamali had just reconquered the region, and a memorial shrine was built on the site. When Crusader armies advanced, Fatimid Caliph al-Zafir ordered the relic transferred to the safety of Cairo. On August 31, 1153, Husayn's casket was unearthed and carried to the Fatimid capital, where it was placed near the great palaces. The vizier Tala'i ibn Ruzzik later built a separate mosque south of Bab Zuwayla specifically to receive the head, but the transfer never occurred. The relic stayed where it had been placed, and a mausoleum was completed at the site in 1154.

The Ayyubid period brought reconstruction in 1237, but fire destroyed much of the building eleven years later. Only the Ayyubid minaret above the Bab al-Akhdar Gate survives from that era. Mamluk historian Mohiyuddin Abd al-Zahir recorded a striking story about Saladin's treatment of a custodian who had helped bring Husayn's casket to Cairo. Saladin, hunting for Fatimid treasures, subjected the man to escalating torture -- culminating in the infamous "Cap of Centipedes," a punishment designed to bore through the skull. According to the account, the centipedes died instead, and the custodian attributed his survival to having carried Husayn's casket on his head during the journey from Ashkelon. The story, whatever its historical basis, speaks to the reverence surrounding the shrine.

The mosque visitors see today is largely the creation of Khedive Ismail Pasha, who reconstructed it in 1874 as part of his campaign to modernize Cairo along European lines. Wanting the building to reflect his cosmopolitan ambitions, Ismail produced a mosque with Italian Gothic-style arches and Ottoman-style minarets -- an architectural hybrid that would have startled the Fatimid founders. A sacred relics room was added in 1893, containing objects believed to include a linen cloak of the Prophet, a lantern holding four strands of his hair, the staff with which he entered Mecca, and a 501-page copy of the Quran written by Ali ibn Abi Talib on deer skin in Kufic script.

In 1965, a zarih -- an ornamental cage marking a burial site -- was installed over Husayn's tomb. It had been built in Mumbai by Taher Saifuddin, the leader of the Dawoodi Bohra community, and was originally intended for the Al-Abbas Mosque in Karbala, Iraq. According to tradition, the zarih was measured precisely for Karbala but simply would not fit. Saifuddin interpreted this as a sign that the shrine of Al-Abbas ibn Ali -- Husayn's half-brother, martyred alongside him -- would not allow Husayn's resting place in Cairo to go unmarked. The zarih was flown to Egypt and installed at al-Hussein instead. A door laden with silver and gold, built by Mohammed Burhanuddin II, was added in 1986.

The mosque was severely damaged by water infiltration and restored in 1996 by the Supreme Council of Antiquities, which replaced the dome over the tomb chamber with steel. Despite its turbulent structural history, al-Hussein Mosque remains one of the most emotionally charged sites in Cairo. It sits at the intersection of commerce and devotion -- the Khan el-Khalili bazaar presses against its walls, and the neighboring al-Azhar Mosque anchors the scholarly tradition just steps away. During Ramadan and the annual mawlid celebrations, the streets around the mosque fill with pilgrims, vendors, and Sufi processions. For many Egyptian Muslims, a visit here carries a weight that no amount of architectural disruption can diminish.