Nausicaá - Centre national de la mer
Aquarium in Boulogne-sur-Mer, France.
Each edition grades its towns against each other only.

Visitors to Outreau can choose from 9 attractions, 5 museums and 2 châteaux. Look within 5 km of its centre for the 19 places to visit; none is in Outreau. Further afield, V3 is 20 km from the centre.
The rest of the best known are 2 châteaux, 2 attractions and a fort.
AquariumNausicaá - Centre national de la mer2.9 km north, in Boulogne-sur-MerChâteauChâteauChâteau de Boulogne-sur-Mer3 km northeast, in Boulogne-sur-MerFortFortFort de l'Heurt2.3 km west, in Le PortelAttractionAttractionFort d'Alprech2.1 km west, in Le PortelAttractionAttractionBeffroi de Boulogne-sur-Mer2.8 km northeast, in Boulogne-sur-MerChâteauChâteauChâteau de Pont-de-Briques3.2 km southeast, in Saint-LéonardBest known first: by how many Wikipedia and sister-site articles cover each place (Wikidata’s count). It isn’t a ranking of how good they are.
To the northeast lie most of the 19 nearby.
The first 20 on the list, numbered as below. The shape is the commune of Outreau; the orange dot is its centre. © OpenStreetMap contributors · commune boundary: IGN
The two biggest groups: other sights (9) and museums or galleries (5).
Dark: in Outreau. Light: in the communes within 5 km of its centre.
Look within 5 km of its centre for all 19 places listed.
Aquarium in Boulogne-sur-Mer, France.
Boulogne-sur-Mer, Castle & Museum in the French seaport..
Nothing is mapped in Outreau itself; these are within 5 km of its centre.
The standout of the 11 is V3, 20 km from town.
MuseumFort de la Crèche5 km north, in WimereuxChâteauChâteauFort Mahon11 km north, in AmbleteuseMonastery or conventMonastery or conventChartreuse Notre-Dame-des-Prés de Neuville-sous-Montreuil30 km southeast, in Neuville-sous-MontreuilChâteauChâteauCitadelle de Montreuil-sur-Mer29 km southeast, in Montreuil-sur-Mer
Theme parkParc Bagatelle31 km south, in Berck
MuseumCité internationale de la dentelle et de la mode de Calais33 km northeast, in CalaisAttractionAttractionCitadelle de Calais33 km northeast, in CalaisPlaces within 40 km of Outreau with an article in both French and English Wikipedia, nearest first.
Nothing is mapped in Outreau itself, but within 5 km there are Nausicaá - Centre national de la mer, Château de Boulogne-sur-Mer, Fort de l'Heurt and Fort d'Alprech.
5 museums and galleries in town or within 5 km, including Aréna, École-musée, Maison de la Beurière and Château Musée d'Aumont.
The nearest with articles in both French and English Wikipedia: V3 (20 km), Cap Gris-Nez (18 km), Cap Blanc-Nez (26 km), Forteresse de Mimoyecques (20 km).
From OpenStreetMap and Wikidata: named museums, galleries, châteaux, abbeys, gardens, zoos, theme parks and other visitor attractions whose mapped point lies inside the commune of Outreau, then those in the communes within 5 km of its centre, and well-known places within 40 km. Houses, ruins and gardens need a sign they’re open to visitors; places marked private, closed or disused are left out. The historic-monument link is the Culture ministry’s Mérimée record. A place that isn’t mapped isn’t listed, so this isn’t everything there is to see.
Sources: OpenStreetMap (© OpenStreetMap contributors, ODbL), Wikidata (CC0: descriptions, websites, Wikipedia articles), the Culture ministry’s Mérimée database (Licence Ouverte 2.0), IGN commune boundaries. Distances are from the commune’s centre point.
Photos from Wikimedia Commons, each under its own licence (our copy, resized).
Contains public sector information under the Licence Ouverte / Open Licence 2.0 (Etalab): INSEE, DGFiP, the Interior Ministry’s statistics service (SSMSI), the Ministry of Education (DEPP), the Health Ministry’s statistics service (DREES) and the Housing Ministry (Carte des loyers). Commune boundaries: IGN Admin Express.