of the total) out of a total of 1,349 inhabited buildings. There were 347 multi-family buildings (25.7%), along with 231 multi-purpose buildings that were mostly used for housing (17.1%) and 115 other use buildings (commercial or industrial) that also had some housing (8.5%). Of the single family homes 107 were built before 1919, while 85 were built between 1990 and 2000. The greatest number of single family homes (125) were built between 1981 and 1990. The most multi-family homes (96) were built before 1919 and the next most (65) were built between 1919 and 1945. There were 9 multi-family houses built between 1996 and 2000. there were 3,862 apartments in the municipality. The most common apartment size was 3 rooms of which there were 1,306. There were 268 single room apartments and 716 apartments with five or more rooms. Of these apartments, a total of 3,221 apartments (83.4% of the total) were permanently occupied, while 421 apartments (10.9%) were seasonally occupied and 220 apartments (5.7%) were empty. , the construction rate of new housing units was 5 new units per 1000 residents. The vacancy rate for the municipality, , was 0.12%. The historical population is given in the following chart: Heritage sites of national significance The Payerne Abbey church and former convent buildings, the Ancien Tribunal, the Swiss Reformed Church of Notre-Dame and the Fountain du Banneret are listed as Swiss heritage site of national significance. The entire old city of Payerne is part of the Inventory of Swiss Heritage Sites. Twin Town Payerne is twinned with Government Payerne Airport is home to the air investigation division of the Swiss Transportation Safety Investigation Board (formerly the Swiss Accident Investigation Board). Previously this was the head office of the Aircraft Accident Investigation Bureau, before its 2011 merger into the SAIB. Payerne is also the home of a major airbase of the Swiss Air Force. Culture Payerne sausage The Payerne sausage () is local variant on the regional Boutefas or Saucisson vaudois sausage. It is a cold smoked pork sausage in a natural casing and has been a traditional dish since the mid-19th century. The IGP protected Saucisson Vaudois IGP and the partly AOC protected Boutefas sausage are made from pigs that foraged for acorns in Vaud or Fribourg woods and drank local water. While the Payerne sausage is not a protected name, the pigs usually come from the same region and