Beneath the Vatican lie secret archives with ancient documents, accessible only to select scholars with permission.
The island, home to uncontacted Sentinelese, is off-limits to protect them and visitors, as they often respond violently to outsiders.
Mount Athos, a thousand-year Orthodox Christian monastic community, prohibits women and limits male visitor access annually.
Lascaux Caves, known for prehistoric paintings, have been closed since 1963 to protect them from damage.
Ise Grand Shrine, a sacred Shinto site, is rebuilt every 20 years; only selected individuals can enter, public views from afar.