Line 3 is a rapid transit line of the Santiago Metro. Traveling from La Reina in the east towards the center, and Quilicura in the North, Line 3 was originally intended to open in the late 1980s, but the 1985 Algarrobo Earthquake hampered its construction, and a subsequent urban explosion in Puente Alto and Maipú (in the far southeast and mid-southwest respectively) further put its construction on hold, until in the early 2010s construction started. The first phase of the project includes 18 stations, which were completed and opened to the public on 22 January 2019 at a cost of US$1.79 billion.[2][3] The second phase, composed of a three-station extension towards the main square of Quilicura, which was inaugurated on September 25, 2023 with a total project cost of US$378 million.[4][5] Its distinctive color on the network line map is chocolate brown.