Klein-Sinaai is a village near the Dutch border in the Belgian municipality of Stekene in the province of East-Flanders. Until 1976 it was an independent municipality.

In Klein-Sinaai we can find remains of the Abbey of Boudelo which was a cisterciënzer-abbey. This abbey is also known as "Baudeloo" under an older spelling form.

The abbey was founded in the year 1197 when Boudewijn van Boekel (a monk from the Sint-Pieters-abbey in Ghent) installed himself in Klein-Sinaai as a hermit. In the early 13th century the abbey was recognised by the bishop of Doornik. Later in 1578 the abbey was destroyed by Calvinists from Ghent. A few years later the abbey was rebuilt, but this time in Gent itself.


In the "cultuurhistorisch museum" in Sint-Niklaas several archeologic finds of the Boudelo-abbey are on display.

In the 13th century, the Cistercianzers from Sinaai (in the Waasland region) had a refuge here. In the 16th century, after the Iconoclastic Fury, they converted it into a fully fledged abbey. In the 17th century, it was one of Ghent’s largest abbeys. While visiting Ghent at the age of nine, Mozart played the organ in the Late Gothic chapel. At the end of the 18th century the convent community was dissolved. The abbey’s garden was turned into a botanical garden and the chapel now houses a library containing the manuscripts and books gathered from all the libraries in Ghent monasteries that were closed down. This collection formed the basis for the present university library. The chapel is partly hidden, because at the beginning of the 19th century a classical access building was built in front of it. The garden is now a city park and the abbey houses an arts college.