The Madrasa al-Firdaus, located about 150 meters to the southwest of the Madrasah al-Zâhirîyah, generally between the Maqamat and Salihin cemeteries, is the largest and best known of the Ayyubids Madrasa of Aleppo. Due to its location outside the city walls, the Madrasa was developed as a freestanding structure. The Ayyubid building has a stark facade that appears as a solid mass of stone, with eleven domes. Its patron was Dayfa Khatun, the wife al-Zahir Ghazi and the queen of the region between 1236-1243. She is one of the most prominent architectural patrons in Syrian history; she established large endowments for the maintenance and operation of her charitable foundations.

Although the Madrasa has four entrances, three of the secondary ones are now blocked up, leaving the main eastern entrance as the only current entry point inside. The main entrance is typical of Ayyubid architecture, with its elongated and narrow proportions and three-tiered Muqarnas vault. The portal leads to the courtyard through a vaulted corridor. Three large chambers and residential cells are arranged around the rectangular courtyard, which is enveloped by an arcade (Riwaq) on the eastern, western and southern sides, with a large iwan on the northern side. The columns have Muqarnas capitals. The Roman and Byzantine heritage of Aleppo is reflected in this Ayyubid Madrasa as it is the only one with an arcaded courtyard.
 

The southern chamber is used as the mosque which is composed of three domed rooms of equal size, the dome of the central one being higher. Three doorways open into the prayer hall from the south arcade, the two outer ones offset to the axes of the east and west arcades. Much smaller doors connect it to flanking square chambers clearly intended as mausoleum. In the Qibla wall are two windows, both flanked on each side by two air shafts or closets.

The side domes are simple, resting on a collar that fudges the transition to the twelve-sided figure formed at the level of the top of the planar split pendentives. These lateral spaces, which are starkly plain, are separated from the main dome by rather low, pointed arches. By deliberate contrast, the central domed space is rich with ornament, and the transition to the windowed dome is meant to create a unified space. The effect must have been strong before the windows were re-glazed with clear glass (presumably heavy screens were used originally) and the mihrab was surrounded with neon tubes.

This central dome rest on a collar that fudges the transition to the twelve-sided zone of transition proper, in which each side is completely opened by a small window. This zone, two courses high, rests in turn on a cornice carved with Muqarnas cells. This cornice rests on split pendentives in which the surfaces of the split areas are treated as flat Muqarnas compositions, while their central joints are cut away to accommodate Muqarnas Squinches that extend their lowest tiers down into the groin of the corners and rise to a small gored semi dome. Structurally this is rather odd, but visually it works rather well.

The mihrab and its surround fill the center of the open area of the Qibla wall almost to the edges of the Muqarnas split pendentives. In its overall form the mihrab is of the type first represented among extant monuments at the Maqam Ibrahim at Salihin; in its use of interlaced marble it continues the series represented at the Madrasa al-Shadhbakhtiyah and the Madrasa al-Sultaniyah. The filling of nearly the entire lunette above the mihrab is new and as flamboyant as anything else in the Ayyubid architecture of Aleppo.

Enclosed within the knot directly above the apex of the mihrab semi dome is a short inscription. Herzfeld read it as the signature of the artisan, which he could not entirely work out. Jalabi-Holdijk reads the inscription as `amal Hassan ibn `Annan, which is plausible but leads to no further connections. In the arch of the lunette is inscribed Qur'an 38:17–23, which, as Jalabi-Holdijk points out, contains the word mihrab, and is on that count appropriate for use here. The larger meaning of the passage emphasizes King David's greatness and submission to Allah, which, I suspect, was also thought relevant somehow. Jalabi-Holdijk also reads in the interlace the phrase la illaha illa Allah, Muhammad rasul Allah, but while it is possible that the design was so intended, this interpretation may be merely reading in: it is easy to discover the requisite letters in such a design

Side Chambers and Side Wings; While the two chambers to either side of the prayer hall can be entered from it through small doors, they are more obviously intended to be entered from the long halls of the side wings, to which large doorways open. Each of the chambers has a window in its side wall, and in the Qibla wall a window flanked by air shafts, as in the prayer hall. Both are vaulted in the same manner as the side domes of the prayer hall. The side wings contain halls, each covered by three domes, again similar to the corner chambers. These are given over to tombs now, but must originally have been used for the educational functions of the institution.

North Wing; The residential and service areas of the building are packed into the north wing. It is composed of the Iwan-hall on the courtyard; another, deeper Iwan-hall open to the exterior, adored to the courtyard Iwan-hall; north-south corridors running straight through from the courtyard to the exterior on either side of the paired Iwan-halls; corridors connecting the portal with the east arcade and the western north-south corridor with a doorway to the exterior corresponding in plan to the portal; latrines; residential apartments; and other small chambers. Jalabi-Holdijk illustrates and provides an excellent discussion of the nonpublic areas of the north wing, which I have not seen. In these apartments one may note the absence of decoration, the use of the wooden beams as lintels supporting masonry.

The two northern corners of the building were extended beyond the rectangle of the plan, probably in the course of construction, and were added to later on, although the various plans of the building show different conclusions as to what is original and what is later addition. It is worth remembering that this building stood within its grounds, which were surrounded by an enclosure wall, and that the building was open to the grounds to the north. Here the original plan may simply have been too confined to accommodate those functions (and residents) that it was thought should rightfully be housed in the main building, rather than in other buildings on the grounds. These were the places where, as Sibt b. Al-Ajami remarks, the building has been shortened. 

Courtyard Iwan-hall; The great Iwan-hall on the courtyard occupies nearly the full height of the building and is covered by a mitered vault. It is a bit shallower than it is wide. Each of the lateral walls contains three air shafts, and the back (northern) wall originally contained three grilled windows equipped with shutters, which opened onto the north Iwan-hall, cooled by shade and the garden beyond, providing good ventilation.

North Iwan-hall; The north Iwan-hall is deeper than it is wide, and is covered with a barrel vault. That one Iwan-hall should have been covered with a mitered vault and the other with a more sensible and economical barrel vault suggests that the mitered vault was somehow stylish, and thus was considered important for the publicly visible courtyard Iwan-hall. Each of the lateral walls of the north Iwan-hall is equipped with two air shafts, and there is a door in each one, close to the back wall, opening into the corridors that link the courtyard to the garden.

Minaret; Near the northwest corner, on the roof, is a thin cylindrical minaret, obviously later than the main building (though Herzfeld seems to have thought it original). The cylindrical form is the next phase after square and octagonal minarets, and Jalabi-Holdijk fairly dates this example as late Ottoman or even post-Ottoman; her informant dated it to 1250 A.H.