Nagyborosnyo is one of the significant villages of Kovaszna county, it is situated on the territory of former Sepsiszek. It is by the left sideroad of road 121, 17 km from the county center, Sepsiszentgyorgy. Kisborosnyo, Lecfalva, Cofalva, Feldoboly and Kispatak belong to it administratively.
The village center was settled by the feet of the Oltar mountain, on the warp made by the Borosnyo stream rushing down from the Bodza mountains and it is situated 530- 540 meters above sea level. The name of the village originates from a noun of the Slavic Bulgarian language with the meaning: birch land. Its name was first mentioned as Burizon in 1332. Nagyborosnyo had several times been the administrative center of the area, as a fair center and as a craftsmen center too. By the end of the 19th century there were 35 small craftsmen working in the village. More than 1500 people lived in the village, most of them of Hungarian nationality and members of the Reformed Church. The Reformed Church gained popularity here in the 1570s. They started building their church in 1854 and it was inaugurated in 1856. It has a single nave and it is made of bricks. Its organ was made in 1869, it is the work of Scheffer Karoly, organ maker. The pulpit crown was made in 1865. Its oldest bell is from 1693.