endangered World Heritage site
Refers to a UNESCO World Heritage site that is under serious threat and listed as in danger. Often used in the context of the List of World Heritage in Danger.
The site was designated as an endangered World Heritage site.
世界遺産 is a general World Heritage site, while 危機遺産 specifically refers to those listed as endangered.
Compound of 危機 (danger, crisis) and 遺産 (heritage), likely a direct translation of the English 'endangered heritage' in the UNESCO context.