This is the 18480th most frequent Russian word.
являющемся
"Being" or "which is."
Here, 'являющемуся' agrees with 'музею' in case, gender, and number, further describing the museum as part of cultural heritage.
Это здание принадлежит музею, являющемуся частью культурного наследия.
This building belongs to a museum, which is a part of cultural heritage.
In this instance, 'являющийся' agrees with 'документ' and provides additional characteristic information about it, indicating its role in the project.
Она изучает документ, являющийся основой данного проекта.
She is studying the document, which is the foundation of this project.
In this sentence, 'являющемся' serves as a present active participle from the verb 'являться', meaning 'being'. It modifies 'университете', providing extra information about it.