Complex sentence: The old name for this road was "Saltanat Abad", which means "kingdom land", and refers to the palace of the Shah (the last king of Iran), situated at the top of this street.
Split into simpler sentences: The old name for this road was "Saltanat Abad" which means Kingdom Land. It is called so because the palace of Shah (the last king of Iran) is situated at the top of this street.