Bring your credit card or stock up with euros beforehand! There's no money-changing service in St-Denis – it has been superseded in favour of ATMs. You'll find a cluster of banks with ATMs near the junction of Rue Jean Chatel and Rue Labourdonnais; all the main banks and the central post office have ATMs. The only bureau de change is Interchange.
Central Post Office Has ATMs.
Office du Tourisme Housed in a historic building, the St-Denis tourist office has English-speaking staff and can provide plenty of information, maps and brochures. It also runs excellent cultural tours focusing on St-Denis' rich architectural heritage (€20, minimum two people) and biking tours (€25). Bookings for gîtes de montagne (mountain lodges) can also be made here. There's internet and wi-fi access (one hour free).
Gîtes de France Information on chambres d'hôtes (family-run B&Bs).