This chapel in Poland opens only two days a year. It hides over a hundred relics of saints.

The underground chapel in the basilica, designed in the 17th century, houses over a hundred relics of saints from around the world. It opens to pilgrims in early November, showcasing items like a small altar and various containers holding relics, including those of St. John Paul II and St. Maximilian Kolbe. Relics, derived from the Latin 'reliquiae', refer to the remains or belongings of saints, and are venerated by the faithful in special reliquaries.