The Suleymaniye is the largest square-based semidomed mosque (3100 m2) to have been designed by Sinan. The two semidomes are situated in the direction of the mihrab (niche indicating the direction of Mecca), a plan we see in Saint Sophia, and later in the Beyazid Mosque ( 1506). Sinan had a very strong desire to surpass Saint Sophia, which was very much admired by the Turks. It may have been at the sultan’s request that he opted for a plan similar to that of Saint Sophia. However, if the two buildings are indeed similar in terms of their general plan, the Suleymaniye is superior to Saint Sophia in terms of proportions, space, and the rationality of the bearing system, as well as both its interior, and exterior perception. The differences between the two religions in their approach to space have also had an impact on the building.
The transition between the central and lateral naves is provided by two small and one large arch. The same rhythm can be noticed on the lateral facade and the cupolas covering the lateral naves. In the flanks, the arches supporting the dome end in a series of graded steps. The arches are filled with a partition wall pierced with windows. At a lower level, the lateral naves are covered by a: rhythmic succession of large and small cupolas. Sinan claims he was the first t implement such a design. With all these gradations, the mass of the mosque takes on pyramidal external proportions.
On the sides, two-storeyed eaved porticoes are situated between the dome supporting piers that gradually descend to the ground. This new solution, first implemented in the Sehzade Mosque, is repeated in its two-storeyed version of the Suleymaniye and the Selimiye mosques. Such external porticoes or gallerie met with great success and would continue to be used in large mosques after Sinan. Water taps for ritual washing were installed below the porticoes at the basement level. The mihrab facade on the other hand does not exhibit the same level of achievement, appearing as a mere buttressed retaining wall. As, for the minarets, they are situated at each of the four corners of the courtyard. The two nearest to the mosque are 76 m. high and decked with three balconies, while the two on the other side of the courtyard are 56 m. high and have two balconies. The main portal of the courtyard is very high and furnished with three rows of windows, giving a palatial appearance to the facade, an effect. which Sinan did not try to achieve in his later works.