The Sister Churches (Norwegian: Søsterkirkene) consist of two late 12th-century churches built side by side at Granavollen, Gran, Hadeland, in Norway.
According to local folklore, the two churches were commissioned by two sisters who had fallen out and therefore would not be seen in the same church. It is, however, not uncommon for medieval churches with different functions to be built close to one another.
The larger of the two churches is called Nikolaikirken (St. Nicholas Church). This church probably acted as a church for Hadeland parish and can seat around 250 people. Because of later rebuilding it is difficult to establish an exact date of construction. Based on stylistic evidence, however, it is thought that the church was built sometime between 1150 and 1200. The church is built as a basilica church with solid Roman columns and plastered walls. Much of the original interior has been lost in fires and in subsequent rebuilding.
The smaller of the churches is Mariakirken (St. Mary Church), a single nave church, which either acted as a monastic church or a church for Gran parish. It was built sometime before 1150, and contains Romanesque and Gothic elements. A fire in 1813 gutted the church and it was not rebuilt until 1859. Until recently it was used as a chapel, but is now open for normal services. It can seat around 150 people.
In the south-eastern part of the churchyard there is a medieval stone tower, Klokketårnet, the original function of which is unknown. It is possible that the tower, which from the mid-19th century was used as a bell-tower, was originally used as a defence tower or refuge. The 11th century Granavollen Runestone can be found behind Nikolaikirken.
The towers of the Søsterkirkene form the base coat of arms to Gran municipality. Noted poet and journalist, Aasmund Olafsson Vinje, is buried in the cemetery of Søsterkirkene. A monument with a bust of Vinjes by sculptor Brynjulf Bergslien was erected at the site.