From Destinypedia, the Destiny wiki
Skyline is a Crucible map located in the Buried City within Meridian Bay on Mars. It is a receiving area for the Clovis Bray research facility, and overlooks Freehold. An elevated rail car marks one end of the map. The center is dominated by a hologram of Mars and the Traveler.
ARENA DESIGNATION: Skyline
This Clovis Bray center served as a hub to several company assets across Meridian Bay and beyond. Though a transit system connects the various Bray facilities, the exact breadth of the network has been lost to time. The Vanguard intends to shed light on the mystery.
But for now, Vanguard researchers have learned all they can from Skyline.
It’s Lord Shaxx’s turn to scrutinize it.