This mosque was built in 1339, just 13 years after the conquest of the city by the Orhan, son of Osman who captured Bursa and made it the first Ottoman capital. The mosque has been repeatedly restored. It has a T-form ground plan.

In 1413 already, the mosque was damaged, as a result of the Karamanoğlu attack against Bursa (which happened
at a time that Bursa was left without proper defence, due to the civil war between the sons of Sultan Bayezid I). It was restored in 1417, but had to suffer from fires and earthquakes several times. The actual building is, therefore, a heavily restored ‘royal’ mosque. Its ‘inverted T’ ground plan is well recognizable on this picture of the interior;
the Orhan Gazi Mosque is reported to be the very first of this type.

The T-form ground plan of the congregation hall of early-Ottoman mosques (the so-called ‘Bursa-type’ mosques) is derived from the late-Seljuk medrese-with-covered-courtyard, with three large iwans (half-open rooms) opening upon a central space. In this mosque, these four rooms are still distinct from each other: their floors are not on the same level.
As the first Ottoman rulers (at least up to their conquest of Constantinople) had strong ties with various Sufi Orders, it is clear that the Bursa-type mosques were designed as multi-functional buildings to meet the needs of these brotherhoods: a place to worship (the ‘mihrab’-room), but also to teach and debate (the ‘iwan’-rooms on the left and right) and even to stay overnight (for this purpose, the Orhan Camii has two smaller rooms on both sides of the vestibule).

Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Türkiye Tarihi Yerler Kılavuzu’ – M.Orhan Bayrak, Inkılâp Kitabevi, Istanbul, 1994.
‘Encyclopedia of the Ottoman Empire’ - Gábor Ágoston & ‎Bruce Alan Masters, 2009
‘Islamic Architecture: Ottoman Turkey’ (Godfrey Goodwin) – London 1977 & Website of ‘nkfu.com’ .