Nicaea

Ancient Nicaea lies under and around modern İznik; the town still sits inside its ancient walls and keeps the old grid of streets, so a visit here is a walk through town rather than a ticketed ruin. Start with the walls: the Istanbul Gate and the Lefke Gate are the best preserved, and you can follow long stretches of the circuit from outside.

At the crossing of the two main streets stands Hagia Sophia, the church where the Second Council of Nicaea met, now used as a mosque; visit outside prayer times and dress modestly. The İznik Museum, in the 14th-century Nilüfer Hatun almshouse, shows archaeological finds alongside the town's famous glazed tiles and ceramics; the Green Mosque opposite makes a short extra stop. The excavated Roman theatre is in the south-west of town. On the lake shore, the remains of a basilica lie in shallow water, and depending on water levels and clarity you can make them out from the shore. Half a day covers the town; a full day lets you add a visit to one of the tile workshops.

İznik is an easy day trip from Bursa, and reachable from Istanbul via Yalova. The town is flat and good for walking or cycling. The lakefront is a pleasant place to end the day. Check the hours on the museum page.