Adjective, very old.
Ancient
Adjective: very interesting.
Fascinating
Noun: a place where a building used to be, or where something happened.
Site
Adjective: something that no one can understand or explain.
Mysterious
Noun, an object that was made by a person
Artifact
Noun, facts that make you believe something is true.
Evidence
Noun: something to try to find out what happened.
Investigation
Adjective: unusual and difficult to understand.
Strange