Standing in walled gardens amid symphonies of birdsong, 4km west of centre, is this fine 13th-century church-turned-mosque retaining some carved reliefs and colourful Christian-era murals. The bay views are lovely especially at sunset. In addition, there's a 1427 stand-alone bell tower and the remains of a 2nd-century Roman temple that was unearthed in 1997.
The centrepiece, originally called Hagia Sophia (Church of Divine Wisdom), was built between 1238 and 1263, and shows both Georgian and Seljuk design influences, though the wall paintings and mosaic floors follow the prevailing Constantinople style of the time. It was converted to a mosque after the Ottoman conquest in 1461, used as an ammunition-storage depot and hospital by the Russians after 1916, restored in the 1960s and partly reconverted to a mosque in 2013. At the time of research, the main interior was closed but the vaulted western narthex, with its extensively preserved frescoes of various biblical themes, remained accessible. A photo board outside shows you more from the interior.
Set amid column remnants, Ottoman gravestones and an old-world corn-store barn, the site's basic garden cafe is a relaxing place for tea or inexpensive local snacks. Or walk out of the gardens' gate and descend the steps to find the much suaver Sofia Garden Cafe & Brasserie.
You can get pretty close to Aya Sofya using a Fatih dolmuş (₺2.50) starting from a stand one block west of Atatürk Alanı. The ensemble is visible from the north as you drive by on the D010 highway. Entrance to the garden is only possible from the south side.