A natural monument is a natural or natural/cultural feature of outstanding or unique value because of its inherent rarity, representative of aesthetic qualities or cultural significance.
Under World Commission on Protected Areas guidelines, natural monuments are level III, described as:
This is a lower level of protection than level II (national parks) and level I (wilderness areas).
The European Environment Agency's guidelines for selection of a natural monument are:
Natural monument sign in Heiligengrabe-Glienicke
Natural monument sign in Gran Canaria