Photography: Florian Koenigsberger Words: Abigail  Covington A winding path leads guests up to the cathedral-like gates of Green-Wood Cemetery where two giant gothic arches lit up in neon blue and purple signify the way forward. A woman dressed to resemble a corpse wanders quietly over to a crowd and gently ushers them down a dimly lit walkway, towards the evening's festivities. "Welcome to Nightfall," she whispers ominously.  Nightfall is Green-Wood's final event of the season. It's a winding walking tour through the cemetery's famous grounds featuring chance encounters with musicians, performers, storytellers, and more. "It's the second year we've done