This lesser-known residential part of Ostend was once in ill repute, but savvy homebuyers have recently snapped up its wealth of utterly charming art nouveau/belle epoque townhouses, restored them and transformed the neighbourhood into a very desirable part of town. There's nothing in particular to do but wander the narrow streets admiring the architecture's finer details, or maybe picnicking in the lovely little park.
Follow Tourhoutesteenweg south of the Casino for about 1km until you reach Oude Molenstraat, then walk down the street admiring the facades until you reach Prinsenlaan.