The cathedral of Laon is one of the most important creations of the art of the 12th and 13th centuries. It took the place of the old cathedral, burned at the beginning of the communal struggles mentioned below. The building is cruciform, and the choir, instead of being apsidal, terminates in a straight wall. Each of the three façades formerly had two towers with spires, and there was also a great central tower. Of these only four remain, and, being without spires, they give the building the aspect of a strong castle. The west front ranks next to that of Notre Dame at Paris in purity. The chapter house and the cloister contain beautiful specimens of the architecture of the beginning of the 13th century. The old episcopal palace, contiguous to the cathedral, is now used as a court-house. The front, flanked by turrets, is pierced by great Pointed windows. There is also a Gothic cloister and an old chapel of two stories, of a date anterior to the cathedral. The church of St Martin dates from the middle of the 12th century. The old abbey buildings of the same foundation are now used as the hospital. The old 12th century chapel of the Templars now forms part of the establishment of the Brothers of Christian Doctrine. The church of the suburb of Vaux near the railway station dites from the 11th century. Numerous cellars of two or three stories have taken the place of the old quarries in the hill-side. The old ramparts have been demolished, but the 13th century gates of Ardon, Royer, and Chenizelles have been preserved. The Société Académique of Laon has collected in its museum of arts and antiquities many archaeological treasures, among others a striking. Roman mosaic of the 2d century, representing Orpheus charming the animals by his lyre, and some Roman ewers, noticeable for quality of metal and purity of form. The communal library contains 30,000 volumes, mostly from the neighbouring convents; it has also interesting manuscripts and autographs, the most ancient of which, signed by Lothair, bears date 972. Laon owes its rank as capital of the department to its central position and to its age; it numbers only 12,000 inhabitants, and has hardly any trade. The surrounding district produces vegetables and beet root; the latter crop supplies the sugar-works, which come close to the foot of the hill; but in the town itself the only industries are coopering and the manufacture of blankets and common woollen stuffs.

In virtue of its geographical position, the hilly district of Laon has always had some strategic importance. Even in the time of Caesar there was a Gallic village where the Remi (inhabitants of the country round Rheims) had to meet the onset of the confederated Belgi. Whatever may have been the precise locality of that battlefield, Laon was fortified by the Romans, and successively checked the invasions of the Franks, Burgundians, Vandals, Alani, and Huns. St Remigius, the famous archbishop of Rheims who baptized Clovis, was born in the Laonnais, and it was he who instituted the bishopric of the town. Thenceforward Laon was one of the principal towns of the kingdom of the Franks, and the possession of it was often disputed. Charles the Bald had enriched its church with the gift of very numerous domains. After the fall of the Carlovingians Laon took the part of Charles of Lorraine, their heir, and Hugh Capet only succeeded in making himself master of the town by the connivance of the bishop, who, in return for this service, was made second ecclesiastical peer ot the kingdom. Early in the 12th century the communes of France set about emancipating themselves, and the history of the commune of Laon is one of the richest and most varied. The citizens had profited by a temporary absence of Bishop Gaudri to secure for themselves from his representatives a communal charter, but he, on his return, purchased from the king of France the revocation of this document, and recommenced his oppressions. The consequence was a revolt, in which the episcopal palace was burnt and several of his partisans were put to death. The fire spread to the cathedral, and reduced it to ashes. Uneasy at the result of their victory, the rioters went into hiding outside the town, which was anew pillaged by the people of the neighbourhood, eager to avenge the death of their bishop. The king alternately interfered in favour of the bishop and of the inhabitants till 1239. After that date the liberties of Laon were no more contested. But it retained its strategic importance, and during the Hundred Years’ War it was attacked and taken by the Burgundians, who gave it up to the English, to be retaken by the French after the consecration of Charles VII. Under the League Laon took the part of the Leaguers, and was taken by Henry IV. During the campaign of 1814 Napoleon tried in vain to dislodge Blücher from it. In 1870 an engineer blew up the powder magazine of the citadel at the moment when the German troops were entering the town. Many lives were lost; and the cathedral and the old episcopal palace were damaged by the explosion. At the Revolution Laon permanently lost its rank as a bishopric.