AIX-LA-CHAPELLE, or in German AACHEN, a district in the Prussian province of the Lower Rhine, with an area of 1600 square miles. It comprehends 10 circles, 15 cities, 12 market-towns, 789 villages, 65,401 dwelling-houses, and in 1849 contained 411,525 inhabitants, of whom 395,416 were Roman Catholics, 2685 Jews, and the remainder Protestants. The circle of the same name extends over 124 square miles, and has a population of 63,458.