Early Ottoman architecture developed through several stages during the 14th and 15th centuries, prior to the advent of what is generally considered "classical" Ottoman architecture in the 16th century. Ottoman architecture began as a continuation of earlier Seljuk and Beylik architecture while also incorporating local Byzantine influences. The new styles took shape in the capital cities of Bursa and Edirne as well as in other important early Ottoman cities such as Iznik.
Three main types of structures predominated in the early period: single-domed mosques (e.g. the Green Mosque in Iznik), "T-plan" buildings (e.g. the Green Mosque in Bursa), and multi-domed buildings (e.g. the Great Mosque of Bursa). Religious buildings were often part of larger charitable complexes (külliyes) that included other structures such as madrasas, hammams, tombs, and commercial establishments.
The Üç Şerefeli Mosque in Edirne, completed in 1447, features a wide arcaded courtyard leading to a prayer hall dominated by a huge central dome. Its design marked a major step in the evolution towards the form of later imperial mosques. After the conquest of Constantinople in 1453 by Mehmed II, the first Ottoman imperial mosque in the city was the Fatih Mosque completed in 1470. Its design demonstrated an increasing influence of the ancient Hagia Sophia on Ottoman architects while also setting a precedent for vast külliye complexes with a highly organized site plan. The Mosque of Bayezid II, completed in 1505 in the same city, is often considered the culmination of architectural developments of the 15th century and the final step leading to the classical style of the 16th century.
Early developments (up to the reign of Mehmed I)
Background
The first Ottomans were established in northwest Anatolia near the borders of the Byzantine Empire. Their position at this frontier encouraged influences from Byzantine architecture and other ancient remains in the region, and there were examples of similar architectural experimentation by the other local dynasties of the region. The first Ottoman structures were built in Söğüt, the earliest Ottoman capital, and in nearby Bilecik, but they have not survived in their original form. They include a couple of small mosques and a mausoleum built in Ertuğrul's time (late 13th century). Bursa was captured in 1326 by the Ottoman leader Orhan. It served as the Ottoman capital until 1402, becoming a major center of patronage and construction. Orhan also captured İznik in 1331, turning it into another early center of Ottoman art.
The late 14th century and the early 15th century was furthermore a period of political and cultural interaction between the Ottoman state, the other Anatolian Beyliks, the Mamluk Sultanate, and the Timurid Empire. Some of the Anatolian dynasties employed Syrian architects in this period. In western Anatolia, the İsa Bey Mosque in Selçuk (1374–5) built for the Aydinids and the Grand Mosque of Manisa (1367) built for the Saruhanids were both designed by architects from Mamluk Syria and inspired by the layout of the Umayyad Mosque in Damascus (early 8th century). Ottoman and Anatolian architecture of this era thus absorbed architectural ideas from Timurid architecture, Mamluk architecture, and older Islamic monuments in these regions.
One of the early Ottoman stylistic distinctions that emerged was a tradition of designing more complete façades in front of mosques, especially in the form of a portico with arches and columns. Another early distinction was the reliance on domes. The main construction materials were brick and rubble masonry. The preference for bricks may have been influenced by Byzantine practice, while their relative lightness also made them well-suited for dome and vault constructions. It was also common for walls to be built with layers of brick alternating with layers of cut stone, a technique inherited from Byzantine architecture. Though there was no standard, a typical construction of this kind would employ three layers of bricks for one layer of cut stone.
In this early period there were generally three types of mosque or religious building: the single-domed mosque, the T-plan mosque or zaviye, and the multi-unit or multi-dome mosque. In early Ottoman society, the Sufi religious orders were the most important organisations that mobilized people and organized religious life; the Sunni ulama (religious scholars and jurists) only became leaders of religious life later, as the Ottoman state evolved. As a result, the most important type of religious building up until the first half of the 15th century (until the reign of Murad II) was the zaviye (from Arabic zawiya), a multi-functional religious structure that accommodated Sufi brotherhoods. While mosques in the strict sense were also built, the major foundations sponsored by early Ottoman sultans were zaviyes rather than mosques. Madrasas (), which catered to the ulama, were likewise less important and less numerous until later periods. Many of the early zaviyes were later converted into formal mosques during the 14th and 15th centuries, a conversion which was expressed architecturally by the addition of minarets (sometimes of crude appearance).
Single-domed mosques
The Hacı Özbek Mosque (1333) in İznik is the oldest Ottoman mosque with an inscription that documents its construction. It is also the first example of an Ottoman single-domed mosque, consisting of a square chamber covered by a dome.Vibhavari Jani, Diversity in Design: Perspectives from the Non-Western World, (Fairchild Books, 2011), 135. It is built in alternating layers of brick and cut stone, similar to Byzantine examples. The dome is covered in terracotta tiles, which was also a custom of early Ottoman architecture before later Ottoman domes were covered in lead. Other structures from the time of Orhan were built at İznik, Bilecik, and in Bursa.
Single-domed mosques continued to be built after this, such as the example of the Green Mosque in Iznik (1378–1391), which was built by an Ottoman pasha. The Green Mosque of İznik is the first Ottoman mosque for which the name of the architect (Hacı bin Musa) is known. It is notable for its careful exterior design and decoration (although this was damaged in the 20th-century Greco-Turkish War), as well as for the antechamber preceding the large domed chamber. The main dome covers a square space, and as a result the transition between the round base of the dome and the square chamber below is achieved through a series of triangular carvings known as "Turkish triangles", a type of pendentive which was common in Anatolian Seljuk and early Ottoman architecture.
An example of a single-domed mosque with a much larger dome can be found in the Yildirim Bayezid I Mosque in Mudurnu, which dates from around 1389. The ambitious dome, with a diameter of 20 meters, was comparable to much later Ottoman mosques but it had to be built closer to the ground in order to be stable. Instead of Turkish triangles the transition is made through squinches that start low along the walls.
"T-plan" mosques and zaviyes
In 1334–1335 Orhan built a mosque outside the Yenişehir Gate in İznik which no longer stands but has been excavated and studied by archeologists. It is significant as the earliest known example of a type of a zaviye, also known as a "T-plan" mosque or "Bursa-type" mosque. This type of building is characterized by a central courtyard, typically covered by a dome, with iwans (domed or vaulted halls that are open to the courtyard) on three sides, one of which is oriented towards the qibla (direction of prayer) and contains the mihrab (wall niche symbolizing the qibla). The front façade usually incorporated a portico along its entire width. The iwans on the side and the other various rooms attached to these buildings may have served to house Sufi students and traveling dervishes, since the Sufi brotherhoods were one of the main supporters of the early Ottomans.
Variations of this floor plan were the most common type of major religious structure sponsored by the early Ottoman elites. The "Bursa-type" label comes from the fact that multiple examples of this kind were built in and around Bursa, including the Orhan Gazi Mosque (1339), the Hüdavendigar (Murad I) Mosque (1366–1385), the Yildirim Bayezid I Mosque (completed in 1395), and the Green Mosque built by Mehmed I. These mosques were all part of larger religious complexes (külliyes) that included other structures offering services such as madrasas (Islamic colleges), hammams (public bathhouses), and imarets (charitable kitchens).
The Green Mosque in Bursa, according to its inscriptions, was begun in 1412 and completed in December 1419 or January 1420 (Dhu'l-Hijja 822 AH), but its extravagant tile decoration is recorded as being completed in August 1424 (at the end of Ramadan 827). The tile decoration, which is present in both the mosque and the nearby mausoleum (Green Tomb) that accompanies it, is the first instance of this type of decoration in Ottoman architecture. The tiles are made in a cuerda seca technique which may have been imported to the region at this time by master tile-makers who were brought here from Tabriz in western Iran, which was under Timurid control. The Trabrizi origins of the craftsmen are recorded in some of the inscriptions. Scholar Doğan Kuban notes that the decoration of the mosque and tomb as a whole was likely a product of collaboration between craftsmen of different regions and that this was in line with the nature of Anatolian Islamic art and architecture in the preceding centuries.
Notable examples of T-plan buildings beyond Bursa include the Firuz Bey Mosque in Milas, built in 1394 by a local Ottoman governor, and the Nilüfer Hatun Imaret in Iznik, originally a zaviye built in 1388 to honor Murad I's mother. The Firuz Bey Mosque is notable for being built in stone and featuring carved decoration of high quality. Two other T-plan examples, the Beylerbeyi Mosque in Edirne (1428–1429) and the Yahşi Bey Mosque in Izmir (circa 1441–1442), are both significant as later T-plan structures with more complex decorative roof systems. In both buildings the usual side iwans are replaced by separate halls accessed through doorways from the central space. As a result, prayers were probably only held in the qibla-oriented iwan, demonstrating how zaviye buildings were often not designed as simple mosques but had more complex functions instead. In both buildings the qibla iwan is semi-octagonal in shape and is covered by a semi-dome. Large muqarnas carvings, grooving, or other geometrical carvings decorate the domes and semi-domes.
Multi-domed buildings The most unusual mosque of this period is the congregational mosque known as the Great Mosque of Bursa or Ulu Cami. The mosque was commissioned by Bayezid I and funded by the booty from his victory at the Battle of Nicopolis in 1396. It was finished a few years later in 1399–1400. It is a multi-dome mosque, consisting of a large hypostyle hall divided into twenty equal bays in a rectangular four-by-five grid, each covered by a dome supported by stone piers. The dome over the middle bay of the second row has an oculus and its floor is occupied by a fountain, serving a role similar to the sahn (courtyard) in the mosques of other regions. The minbar (pulpit) of the mosque is among the finest examples of early Ottoman wooden minbars made with the kündekari technique, in which pieces of wood are fitted together without nails or glue. Its surfaces are decorated with inscriptions, floral (arabesque) motifs, and geometric motifs.