AARSCHOT, Belgium: During the week, Ivonne Janssens, 57, is a hospital cleaner. But come the weekend, she climbs the narrow steps of a three-story medieval tower and turns into a 14th-century duchess with a faux-emerald necklace, a linen headdress, a leather satchel full of fake gold coins, and a retinue of mercenaries to fend off invading French knights.

Her husband, Daniel Grandjean, a 50-year-old furniture maker with a pot belly and bushy beard, becomes an axe-wielding soldier-for-hire. It was he who convinced the council in this sleepy Flemish town to let the couple live part time in the 700-year-old Sint-Rochus tower, where guards once stood watch to prevent Aarschot, then built of wood and straw, from catching fire.

When not inhabiting the tower, the spouses sleep in a medieval-replica bed at home. They avoid eating tomatoes or drinking coffee because Columbus had yet to discover America in the Middle Ages and such foods were not available in what was to become Belgium. Carrots are also off the menu because they grow in the ground and the medieval church deemed them the food of the devil.