Otoyol 21
| O-21 | ||||
|---|---|---|---|---|
| Ankara-Tarsus Motorway Ankara-Tarsus Otoyolu | ||||
| Route information | ||||
| Part of E90 | ||||
| Length | 432 km (268 mi) | |||
| Major junctions | ||||
| From | Gölbaşı, Ankara | |||
| To | Tarsus, Mersin | |||
| Location | ||||
| Country | Turkey | |||
| Regions | Central Anatolia, Mediterranean | |||
| Provinces | Ankara, Konya, Aksaray, Nevşehir, Niğde, Adana, Mersin | |||
| Major cities | Niğde, Tarsus | |||
| Highway system | ||||
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Otoyol 21 (English: Motorway 21), abbreviated as O-21, a.k.a. Ankara-Tarsus Otoyolu (English: Ankara-Tarsus Motorway), is a completed toll motorway in the Central Anatolia and Mediterranean regions in Turkey. Currently, it connects Otoyol 20 from Gölbaşı, Ankara with the Adana-Mersin Motorway O-51 at Tarsus in Mersin Province. On its full length, it is part of the European E90. The last part of the highway opened on 16 December 2020. With a length of 432 kilometres, the O-21 is the longest motorway in Turkey.