There are regular train services from Paris, leaving from Gare du Nord. As of July 2012, prices from Paris to Laon average about €23 one way (second class). The train station in Laon is located in the new town, at the foot of the medieval city which is on top of a hill.
Walking from the new town to the medieval part of the city is certainly doable, but only if you're fit and don't have heavy luggage with you—the 300ft climb is a steep one. There is a funicular railway which runs from the train station up to the Hotel de Ville (town hall) every five minutes or so throughout the day. It takes about 3 minutes and costs €1.10 one way. There is also a local bus service. If you're bringing a car with you, you should probably park it in the new town, as there is very little parking available in the medieval Haute Ville.
The fine early Gothic cathedral is one of the finest in France, with openwork towers and a four-storey nave elevation. Its architecture influenced many other medieval European cathedrals, including that of Notre Dame in Paris. The interior is extremely light and spacious. The west towers feature an octagonal top storey with square turrets at the angles on top of the square bottom storey. They are decorated with the figures of sixteen oxen, said to commemorate a miraculous ox that appeared to pull a cartload of stone to the hilltop site.
Nearby stand the Hotel Dieu (medieval hospital and almshouse), the cathedral chapter, and the town's museum. The museum in particular has a fine collection of classical antiquities, and the striking 'transi' tomb (showing the effigy of a decaying corpse) of 14th century clergyman and royal physician Guillaume de Harcigny. In the museum's grounds stands a fine twelfth century octagonal Templar chapel, newly renovated.
At the other end of the medieval town, the remains of the abbey of Saint-Martin-de-Laon include its church and some of its associated buildings, including the cloister garden (now the city library's courtyard) and some of the chapter house.
It's worthwhile taking a walk around the town, admiring the houses—almost all built between the 12th and the late 18th centuries—and the spectacular view from the town walls out across the Picard plain.
Climb the cathedral tower. The tourist office, in a twelfth century building next to the cathedral, arranges tours, and it is best to reserve your tickets before time as numbers are limited.
Pave de Laon sweet pastilles.
Les Arcades (place du Général Leclerc) is centrally located and good for people watching, but over-priced and the food isn't great. The service was also pretty indifferent.
Brasserie Le Parvis's (3 Place du Parvis Gaultier de Mortagne) main selling point is its location—sitting outside, you can have your meal while looking up at the cathedral. The service was better here but still a little distracted.
Hotel de la Banniere de France is located just behind the Hotel de Ville in the historic centre of the city.
The Hotel des Chevaliers, located on the rue des Seruriers just beside the Hotel de Ville (town hall) is good for the budget traveller. The upstairs rooms have been tastefully renovated; the rooms on the first floor are in a little bit of a Seventies time warp but all are comfortable and spotlessly clean. The owner is very friendly, lots of good suggestions for places to go.