This is the 17218th most frequent Russian word.
строгоохраняемого
"Strictly protected."
Used as an adjective describing a site that is strictly protected or guarded.
Вход на территорию строгоохраняемого объекта запрещен.
Entry to the territory of the heavily guarded site is prohibited.
Here, the word describes an archive that is guarded or protected to an exceptionally high degree.
Документы по делу хранятся в строгоохраняемого архива.
The documents related to the case are stored in a strictly protected archive.
Used to describe a natural area that is preserved and guarded rigorously due to its environmental importance.