Arras' Flemish Gothic city hall dates from the 16th century but was completely rebuilt after WWI. Four géants (giants) live in the lobby. For a panoramic view, take the lift (plus 43 stairs) up the 75m-high, Unesco-listed belfry. Or, for a subterranean perspective, head down into the souterrains (caves) under the square, also known as boves, which were turned into British command posts, hospitals and barracks during WWI.
Tours of the boves (40 minutes; in English upon request) generally begin at 11am, with at least two more departures in the afternoon. City hall tours run at 3pm Sunday year-round, with an additional tour at 3pm Monday to Friday July and August. Tickets are sold at the tourist office (on the ground floor).