Although Bursa Great Mosque (Ulu Cami) is the city's largest, the Green Mosque (Yeşil Cami, YESH-sheel jah-mee) is its architectural gem, exemplifying the movement from the hypostyle Ulu Cami to the great domed mosques of Edirne and Istanbul.
The Green Mosque, commissioned by Sultan Mehmet I Çelebi and finished in 1424, is set on a promontory overlooking the valley (now urban sprawl). It takes its name from the green-blue tiles of the interior.
Behind the mosque to the south is the pretty, harmonious octagonal Green Tomb (Yeşil Türbe). The tomb was covered in blue tiles during restoration work in the 1800s. It is again under restoration (2008). If you have the chance to glance inside, you'll see the richly tiled cenotaphs of Sultan Mehmet I and his family.
Just down the hill to the west of the Green Mosque is Bursa's Turkish & Islamic Arts Museum, set up in the historic medrese (theological college) that was part of the mosque complex. It has a good collection of historical objects and art, and is worth seeing for the building itself.
To the east of the Yeşil Cami complex, uphill a short ways through the cemeteries, is the Emir Sultan Mosque.
You can walk downhill from the Green Mosque complex to the center of Bursa in 15 to 20 minutes, or take any passing bus.
Its main portal, of marble richly worked, was once sheltered by a columned porch which, along with much of the mosque, was destroyed by earthquake in 1855. (The main part of the mosque was authentically rebuilt, but the porch was not.)
Above the portal, reached by a small staircase inside, is the sultan's loge (hünkâr mahfili), decorated in gilded tiles, but usually not open to the public.
The mosque's domed central hall is flanked by rooms to left and right that were used for both prayer and for conducting Ottoman government affairs. The main prayer hall is the room with the 15-meter (49-foot)-high mihrab (prayer niche), opposite the portal.