Kaynarca, historic Genna (Greek Γεννα, Bulgarian Яна), is a town in Kırklareli Province (historic Eastern Thrace). There are ruins of a church and a rock-cut complex in the town center.

The town was known as Genna in the Late Ottoman era. Its earlier history is completely unknown. The region was captured by the Latins in 1204. It was under Ottoman control by 1368, when Bizye (modern Vize) was captured. It was located on the regional road north of the Via Militaris, which ran from Skopelos (Yoğuntaş) to the nearby Brysis (Pınarhisar).

Near the center of the town are the ruins of a church, which has been dated to the late tenth or eleventh century. In the nineteenth and early twentieth centuries, it was dedicated to the Panagia (“All-Holy”) Virgin Mary. The church was still in relatively good condition until the population exchange forced the Greeks in the village to migrate in 1923. Only the southern half of the church survives today. It also has traces of its frescoes.

The church had a compact cross-in-square plan measuring 7x7.6 m. It had elongated proportions with a tall, cylindrical drum and blind arcades on the exterior, and it lacked a narthex. Its dome rested on four piers, while the four arms of the cross were covered with barrel vaults. Its masonry was ashlar and rough stonework with the occasional use of brick. It had a distinctive local, non-Constantinopolitan appearance, probably similar to the Church of St. John in Nesebar (historic Mesembria).

A rock-cut complex is on the western side of the town. While it has often been claimed to be a church, it was actually an aristocratic residence with a central courtyard. It consisted of a barrel-vaulted transverse hall and a square kitchen with a conical roof.