Complex sentence: Now crossed by a road (see photo), it used to be impassable by land and was therefore one of the natural defenses that made Kamakura an impregnable fortress, and for this reason, it appears often in the historical record.
Split into simpler sentences: Now crossed by a road (see photo), it used to be impassable by land and was therefore one of the natural defenses that made Kamakura an impregnable fortress. For this reason, it appears often in the historical record.