Paston Great Barn (grid reference ) is a mediaeval barn, near Paston Hall on the southeast edge of the village of Paston, in northeast Norfolk, England. It is owned by the North Norfolk Historic Buildings Trust. It dates from 1581 and is associated with the Paston family. It is a Scheduled Ancient Monument and a grade II* Listed Building.
It is a long, low barn, with a thatched roof, and walls built of brick, flint and limestone. It has large doors with timber lintels. The barn was commissioned by Sir William Paston III as a grain store and threshing barn. It is approximately 70 metres long, 9 metres wide and 16 metres high. It has been granted Grade II* Listed Building status by English Heritage due to its architectural and historical importance. There are three 30-metre long Victorian wings on the eastern side of the barn, added to house cattle.
The barn and its immediate surroundings, an area of 0.95 hectares was notified as a biological Site of Special Scientific Interest by English Nature in 1999, and the site has also been designated as a Special Area of Conservation.
In 2002, English Nature started a 50-year lease of the barn. There is currently no public access into the barn, partly in order to minimise disturbance to the bats, although some educational interpretation at the site is being considered for the future.
The barn is one of only three maternity roosts in Britain for the Barbastelle Bat, a species which is rare at a European scale, and it is the only one of the three which is in a building. The colony was discovered in 1996. The Barbastelles mostly roost in large crevices in timber lintels over the barn doors. Their feeding grounds are believed to include nearby coastal cliffs.
Breeding colonies of Natterer’s Bat (Myotis nattereri), Brown Long-eared Bat (Plecotus auritus) and Common Pipistrelle (Pipistrellus pipistrellus) also inhabit the barn.