Exterior of Biblioteca Joanina.

Preserving such precious volumes demands care, attention, and, in this case, bats.

Given their nocturnal habits, these bats are challenging to encounter while the library is open during the day.

Meet the bats that protect the rare manuscripts housed inside Biblioteca Joanina in Portugal

Exterior of Biblioteca Joanina. (Photo: University Square, viaWikimedia Commons,CC 2.0)

Beyond this, the library offers evening concerts, which typically occur right around a bats dinnertime.

Biblioteca Joanina is only one of two libraries in the world that houses bats alongside its books.

Its monumental facade also combines the simplicity of white and earthy tones alongside decorative pillars that crown the entrance.

Meet the bats that protect the rare manuscripts housed inside Biblioteca Joanina in Portugal

Inside of Biblioteca Joanina. (Photo: xiquinhosilva, viaWikimedia Commons,CC 2.0)

To learn more about Biblioteca Joanina, visit theUniversity of Coimbra website.

Inside of Biblioteca Joanina.

European free-tailed bat, one of the species found within the library.

Meet the bats that protect the rare manuscripts housed inside Biblioteca Joanina in Portugal

Inside of Biblioteca Joanina. (Photo: xiquinhosilva, viaWikimedia Commons,CC 2.0)

Meet the bats that protect the rare manuscripts housed inside Biblioteca Joanina in Portugal

European free-tailed bat, one of the species found within the library. (Photo: Emanuel Yellin, viaWikimedia Commons,CC 3.0)

Meet the bats that protect the rare manuscripts housed inside Biblioteca Joanina in Portugal

Soprano pipistrelles, one of the species found within the library. (Photo: Evgeniy Yakhontov, viaWikimedia Commons,CC 3.0)