Pau is itself a fairly small city of 80,000, and its surrounding towns are even smaller, which means that parking and traffic congestion are rarely problems. Therefore, it is advisable that you rent a car and take a drive outside the city to see some of the Basque countryside. Many of the villages in Béarn are quite picturesque, and the Spanish border is only about 40 miles away if you feel like taking a small road trip.
Getting around the city center can be done on foot. The city is quite old, so there are many historical buildings along the smaller streets that will make the walk worthwhile. However, there is also a public transportation system called S.T.A.P, which consists of 13 bus lines serving 760 stops. The buses run through not only the most popular parts of Pau (including the train station, stadium, and several plazas) but also to a few outlying communities. Tickets can be bought in the form of a single fare, 8-token booklets, or day passes. For somewhat longer stays, there are also weeklong and month-long passes. Be aware, though, that buses stop running around 5pm and only lines A and B of the Noctabus run on Sundays, holidays, and weekend nights.

