According to Strong’s the word used in Revelationis “oros,” which can only mean “mountains”. Rome doesn’t sit on any mountains; it is surrounded by seven hills (”bounos” in Greek). On the other hand, Mecca, is surrounded by seven mountains (Jabal Quba, Jabal al Qinaa, Jabal Li Aali, Jabal Jifan, Jabal Jijad, Jabal Qubais, and Jabal Hindi).
It could also be interpreted that “mountain” is a symbol for kingdom.