Fifty years ago, Lebanon descended into one of the darkest periods in its modern history: the civil war. The brutal 15-year conflict was marked by sectarian violence and shifting front lines. In the capital Beirut, some buildings still bear the scars of battle. Others have been rebuilt, but the trauma remains in people's minds. Our correspondent Serge Berberi spoke to some of those who lived through the conflict and who are trying to keep its memory alive today. He brings us this report, with Rawad Taha.