This is the 18128th most frequent Russian word.
храмом
"Храмом" means "temple" (instrumental case of храм).
In this context, "храмом" is used in its instrumental case form, describing a building characterized as a temple.
Мы проходили мимо старого здания, которое оказалось храмом.
We were passing by an old building, which turned out to be a temple.
Here, "храмом" is used metaphorically in its instrumental case to describe the park as characterized metaphorically as a temple.
Этот парк был раньше храмом природы.
This park used to be a temple of nature.
In this sentence, "храмом" employs a figurative sense to denote a place dedicated to art, using the instrumental case.