The Yesil Mosque, also known as Mosque of Mehmed I, is located on the east side of Bursa, Turkey, the former capital of the Ottoman Turks before they captured Constantinople (known as Istanbul now) in 1453.    Yesil Mosque                                                      Entrance with moc+írabe half-dome.
The construction of the mosque was commissioned by Sultan Mehmed I and completed by the end of 1419 and beginning of 1420. The mosque was built by architect Vezir HaciIvaz Pasha. The artists of painted decorations were Ali bin Ilyas and Mehmed el Mecnun. Following the earthquake in 1855, the building underwent an extensive renovation led by architect Léon Parvillée, as Ahmet Vefik Pasha, the Vali (governor) of Bursa, was unable to find a qualified Turkish architect. Parvillée managed to save the mosque but he lacked experience of the Seljukian and early Ottoman architecture. He was also hampered by shortages of money and skilled labour. The original decorations of the vaults and the walls were not restored. But his whitewash was perhaps to be preferred over botched attempts at reproducing old paintwork.
The architectural style known as Bursa Style begins with YesilCami. The mosque is based on a reverse T-plan with a vestibule at the entrance leading to a central hall flanked by eyvans ( a vaulted recess open on one side) on the east and west and a larger eyvan with mihrab niche on the south. Two small eyvans flank the entryway above which the royal box (hünkarmahfili) is located. There are four rooms with fireplaces to the north and south of side eyvans accessed through the vestibule and the central hall respectively. Stairs on both sides of the vestibule lead to the upper floor where the royal lodge and two adjacent rooms for the royal women are located. Here, a passage opens to the balconies on the northern facade where the minaret steps begin. A portico was designed but never built, because, when the sultan died, work on his private mosque would stop.
The large entrance to the mosque is flanked by recessed marble sofas with twin cubby-holes (papuçluks) for the shoes. Above the door is a long Arabic inscription in bronze. The door is crowned by a half- dome with a cascade of mocárabe (stalactites) that taper into a star. The flat face of the half-dome, set in a ribbed frame, is adorned with arabesques and inscriptions in Rumi scripts. Between the inscription and the mocárabes is a small window that lights the floor of the foyer to the sultan's box. Above the niches on each side of the entrance door is an inscription dedicated to HaciIvaz, who designed the mosque.
Beneath the central dome, the sculpted white marble fountain within an octagonal pool adds to the beauty of the mosque. The walls of the inner vestibule are covered with dark green tiles and, on each side, a great circle filled with blue, white and golden-yellow arabesquesof tendrils and flowers.
The interior of the mosque is decorated with a mosaic of blue-green tiles on the walls and ceiling of the eyvans, from which it gets its name. (The exteriors with its domes, now clad with lead, were once also adorned with blue-green tiles).
Recessed on each side of the vestibule are mahfils (tribune for müezzins), richly decorated with tiles and whose ceilings are filled with complex roseate arabesques. The deep blue hexagonal wainscot tiles are somewhat less intricate, with traces of gold embedded. The two tabhane (lodging rooms for travellers) rooms, beyond the eyvans, contain niches and ocaks (fireplaces with a tall hood). A calligraphic inscription in three lines is put in an arch over one of its doors.
The mosque is built out of sandstone and clad with marble panels, a majority of which was replaced in the nineteenth century. Flower designs and scriptures carved in marble frame the entry and the windows, with a different design featured in tympana of every window. The grand entrance and the mihrab niches on the northern facade are crowned with marble mocárabe half-domes. The iron parts used on the door, windows and cupboards of the mosque are proof of excellent workmanship.
The two minarets are later additions to the building. They were both rebuilt on an old base by Parvillée. They have been fitted with stone spires carved in the baroque manner at the time of renovation. They can only be accessed through the sultan's apartments and the climbing up the winding stairs to the attics.