Complex sentence: The restoration of two historic bridges, Gwangtonggyo and Supyogyo, was also a contentious issue, as several interest groups voiced opinions on how to restore historical and cultural sites and remains, and whether replace the bridges or not.
Split into simpler sentences: The restoration of two historic bridges, Gwangtonggyo and Supyogyo, was conflictive issue. Each interest group insisted on the topic of how to restore historical and cultural sites and remains; whether replace the bridges or not.