 The parishes of Saint-Aignan (Sanctum Anianum) and Mont-aux-Malades (Monte Infirmorum, which takes its name from a hospital) are mentioned in documents dating back to the 12th century.Henry II built a church there dedicated to Thomas Becket in 1176 in an attempt to make up for his unwitting role in the murder of the Archbishop of Canterbury.The modern commune of Mont-Saint-Aignan was created in the early 19th century (1815–1819) out of the merger of the communes of Monts-aux-Malades, Saint-Aignan and (partly) Saint-Denis-de-Bondeville.