In 1171 the Damascus-appointed governor Salah el-Din (Saladin) overthrew the last Fatimids caliph and seized power himself, establishing the Abbasid dynasty.

Salah El-Din (Saladin) built the Citadel in 1183 A. D. as the centre of government, while simultaneously extending and restoring the city fortifications, with the aim to dominate Cairo from Mokattam Hills. This huge project was incomplete at his death, and much work continued in later times. Cairo is the best preserved of all Islamic cities, and substantial parts of Salah el-Din's structures remain today. In spite of the impounding of the defensive towers, the Cairo Citadel is, from a military point of view, slightly less substantial than the Citadel of Aleppo (In Syria), but it remains one of the most notable existing examples of Muslim military architecture. The skilful masonry work, and the impressive vaulting in particular have no precedent in Egypt.
 

After the death of Salah al-Din, his nephew, Al-Kamel, reinforced the Citadel by enlarging several of the towers.  Specifically, he encased the Blacksmith's Tower & the Sand Tower making them fully three times larger.  These two towers controlled the narrow pass between the Citadel and the Mokattam Hills. Al-Kamel also built a number of great keeps (towers) around the perimeter of the walls. 

These massive structures were square, up to 25 meters (80 ft) tall and 30 meters (100 ft) wide. In 1218, upon the death of al-Kamel's father, now Sultan al-Kamel moved his residence to the Citadel where he built his palace in what is now the Southern Enclosure. While the palace no longer exits, until the construction of the Abdien Palace in the mid-19th century, it was the seat of government for the Country of Egypt. The Citadel consists of three main sections, surrounded by their own walls with towers and gates. These consist of the Lower Enclosure, the Northern Enclosure and the Southern Enclosure which is the Citadel proper (El-Qal'a3). The two main gates are on the north (Bab el-Gadid) and south (Bab el-Gabal). Particularly when viewed from the back side (from the north), the Citadel reveals a very medieval character.

Some of Citadel Monuments Include:

Jewel Palace;

Jewel Palace (Qasr el-Jawhara), originally Mohammad Ali Pasha's headquarters, is now open to the public as an example of the best early 19th century Ottoman decoration and architecture. Constructed in 1814, it includes a small garden leading to a mosque with one of the more interesting eccentricities being the Watch Hall where the shape of a watch has been used to decorate the walls. Its collection includes 19th century royal portraits, costumes and furnishings.

Mohammed Ali Mosque;

The Police Museum;

The police Museum was built over the site of the Mamluk Palace just opposite the Mosque of An-Nasser Muhammad. It's host of law enforcement displays dating back to the dynastic period.  In 1983 a hall from the Palace was discovered masked deep beneath rubble, and can be seen at the southern end of the terrace with it's majestic view of Cairo.

An-Nasser Mohammed Mosque;

An-Nasser Mohammed Mosque was once the principle mosque within the Citadel. It was constructed in 1335 by Sultan an-Nasser Mohammed as a congregational mosque, it has two unique minarets topped in a pincushion style dome design with glazed faience decoration, and covered in blue Persian-style faience tiles. Many of the Mosque's columns were taken from pharaonic (pharaohs), Roman and Byzantine buildings. The Mosque today is fully restored and is one of the best preserved examples of Mamluks architecture.

The Military Museum;

The Military Museum, located in the Citadel, contains a collection of weapons and costumes illustrating warfare in Egypt from ancient times. Notable are its artifacts of the 1956 Anglo-French-Israeli attack.

The Carriage Museum;

The Carriage Museum, within the Citadel, is housed in the building once used as the British Officers Mess during the colonial period. It has a collection of eight carriages, including that of the Khedive Ismael used when he opened the Suez Canal in 1869 and a golden state carriage presented to the Khedive by Napoleon III.

The Archeological Museum;

The Egyptian government established the ‘Service des Antiques de Egypt’ in 1835 mainly to halt the plundering of archeological sites and to arrange the exhibition of  the collected artifacts owned by the government. The Azbakian garden in Cairo was first used as a storage place for these artifacts. The collection was later transferred to another building in the citadel of Salahdin.
 

In 1858, a museum was prepared at Boulaq, its contents collected by the French archeologist August Mariette. In 1880, the contents of the Boulaq museum was transferred to an annex of the Giza palace of Ismail pasha, the ruler of Egypt. The present museum was built in 1900, in the neo-classical style by the French architect Marcel Dourgnon.

This museum exhibits over 120000 objects, some of the important groups of these objects are: Artifacts from the tombs of kings and members of the royal families of the Middle Kingdom found at Dahshur in 1894.
 

The Suleiman Pasha Mosque;

Sometimes called the Sariya el-Gabal Mosque (after the Fatimids saint Sayyid Sariya whose tomb is at the eastern end of the wall surrounding the Mosque,) this Mosque was built by an Ottoman governor named Suleiman Pasha in 1528. Situated in a small, enclosed garden behind the Military Museum. The single minaret is tall and slender & traditionally Ottomans style. Within the prayer hall, there is a large central cupola and three demy-cupolas, all richly decorated with floral and geometric motifs, and the fine marbled mihrab shows Mamluks influence.

Bab el-Azab (Gate of Pain);

The Bab al-Azab protected the original entrance to the Citadel and was rebuilt in 1754 by Abd el-Rahman Qatkhuda, from which the brass-bound wooden doors date. The gate's infamy spawns from a single but decisive action by Mohammed Ali, the early 19th century governor of Egypt.
 

In March, 1811, five hundred Mamluks chiefs led by high-ranking Turkish army officer marched in the military procession of Mohammed Ali's celebrations as one of his rearguard contingents. As they rode out of the Citadel down the narrow little hill to the gate of Azab, the huge doors of the gate were suddenly slammed shut in front of them, so that they were trapped in a narrow defile with high walls on either side and a detachment of Albanian soldiers behind. There was little chance of escape, as Turkish soldiers high atop the walls poured down a merciless fusillade. In one swoop, Muhammad Ali ended the long domination of the Mamluks in Egypt.

Salah ad-Din (Saladin) Bibliography;

After the death of Nur ad-Din, who was planning to campaign against his too powerful subordinate, Saladin proclaimed himself sultan of Egypt, thus beginning the Abbasid dynasty. He spread his conquests westward on the northern shores of Africa as far as Qabis and also conquered Yemen. He took over Damascus after Nur ad-Din's death and undertook to subdue all of Syria and Palestine. He had already come into conflict with the Crusaders, and he put the rulers of the Latin Kingdom of Jerusalem on the steadily weakening defensive. He was unsuccessful in his efforts to conquer the Assassins in their mountain strongholds, but he took Mosul, Aleppo, and wide areas from rival Muslim rulers and became the principal warrior of Islam.