| Mar Yakov Church (Mor Yakub Church) | |
|---|---|
| Church of Saint Jacob in Nisibis | |
Mor Yakup Kilisesi | |
 Church of Saint Jacob and the surrounding excavation site (January 2023) | |
  Mar Yakov Church (Mor Yakub Church) Location of the church in Turkey. | |
| 37°04′01″N 41°12′55″E / 37.06694°N 41.21528°E | |
| Location | Nusaybin |
| Country | Turkey |
| Denomination | Syriac Orthodox or, Church of the East |
| History | |
| Status | Church |
| Dedication | Jacob of Nisibis |
| Relics held | Saint Jacob of Nisibis |
| Architecture | |
| Style | Late Roman and Early Byzantium architecture |
| Groundbreaking | 313 |
| Completed | 320 |
| Specifications | |
| Number of domes | 1 |
| Administration | |
| District | Nusaybin |
| Province | Mardin |
Mar Yakov Church or Mor Yakup Church (Syriac: ܥܕܬܐ ܕܡܪܝ ܝܥܩܘܒ ܕܨܝܒܝܢ Idto d-Mor Ya'qub d-Nsibin, Turkish: Mor Yakup Kilisesii), also known as the Church of Saint Jacob in Nisibis, is a historic church in Nusaybin, southeastern Turkey. Archaeological excavations revealed that the 4th-century church building was originally the baptistery of a cathedral, which no longer exists. It is not determined whether this church belonged to Syriac Orthodox Church or the Church of the East, but it is under the jurisdiction of the Syriac Orthodox Church which it is most likely linked to.