Paris's definitive children's park is the 25-acre Jardin d'Acclimation in the northern part of the Bois de Boulogne. This is the kind of place that amuses tykes and adults, but not teenagers. The visit starts with a ride on a green-and-yellow narrow-gauge train from Porte Maillot to the Jardin entrance, through a stretch of wooded park. The train operates at 30-minute intervals Wednesday, Saturday, and Sunday from 10:30am until the park closes; one-way fare costs 1.15€. En route you'll find a house of mirrors, an archery range, a miniature-golf course, zoo animals, a bowling alley, a puppet theater (performances Thurs, Sat, Sun, and holidays), a playground, a hurdle-racing course, junior-scale rides, shooting galleries, and waffle stalls. You can trot the kids off on a pony or join them in a boat on a mill-stirred lagoon. La Prévention Routière is a miniature roadway operated by the Paris police: Youngsters drive through in small cars equipped to start and stop, and are required by two genuine gendarmes to obey street signs and light changes. Inside the gate is an easy-to-follow map. The park is circular -- follow the road in either direction and it'll take you all the way around and bring you back to the train at the end.