Driving from Toulouse to AriègeFrom the airport or outskirts of the city, follow signs for TOULOUSE until you see signs for FOIX-TARBES or TARBES-LOURDES. (Because the first Foix-Tarbes sign you see is placed immediately after a turn-off you may think you've just gone past the exit. Ignore the minor surge of panic and carry on.) From centre city, head south toward TOUTES DIRECTIONS until you see signs for FOIX-TARBES. Follow FOIX to go to Pamiers, Foix, Tarascon, Ax via the N20.
The A66 motorway, completed in 2002, has shortened the journey from Toulouse to Pamiers and Foix. Take the A61 toward Narbonne. The A66 is the first exit after toll (péage), direction Andorre and rejoins the N20 at Pamiers. The toll for the A66 is 3.90 euros.
Follow TARBES to go to St Girons via the motorway (A64). Take exit 20 onto the N117 which will lead you straight there.
To take the scenic route to St. Girons or to go to Foix:
Instead of the A64 take the E9 Foix exit (not FOIX PAR RN, which is much slower), following the signs for Foix through one rotary/roundabout. If going to Foix, carry on following the signs.
To go to St. Girons, stay in the right lane after the roundabout and at the second rotary/roundabout a few km later, take the D4 towards Labarthe-sur-Lèze. (Just before the rotary/roundabout a separate lane forms on the right going in that direction. Take it. If you miss it, you can still access it from the rotary/roundabout.)
Continue on this road, which eventually turns into the D9, following signs for Foix, Pailhes, or the Mas d'Azil. The D9 passes through picturesque villages built with the 'Roman' brick typical of the region. Many have their medieval centres and arcades intact.The fortified medieval village of Carla-Bayle is worth a detour, for its splendid view of the surrounding countryside.
At the village of Pailhes, take a sharp right at the stop sign to go towards St. Girons. After Le Mas d'Azil the road winds through a natural tunnel carved by the river over tens of thousands of years. It's less than 30 minutes from St. Girons so if you don't have time for a guided tour of this famous cave you can easily make a return visit.