Los Los is a ghoul city upon the remains of , located in west Texas . The city possesses a dock area and a heavily damaged bridge . The Secret Vault , built by Vault - Tec to protect high - members of Vault - Tec and used to research the latest technologies and the Forced Evolutionary Virus can be found under the city . Background . Before the war , Los Ybanez was one of the Texas metropolis , a thriving and sun - soaked city . For this reason , in addition to being a recluse city , the personal Vault of Vault - Tec , named Secret Vault , was founded under the city in the shadow of the U . S . government . After the Great War , the city was heavily bombed and turned into an ashen canyon of crumbling building and bombed - out bridges , and the amount of dust and radioactive basin plunged the city into an endless night , the sun can not break this artificial fog . Most survivors of this apocalypse were turned into ghoul s . After becoming aware of their condition , their first objective was to establish a " paradise " free of humans and other mutants , where they can live in peace , and the city was renamed " Los " ( play on words between the former name of the city and their status of lost in this devastated world ) . Despite wanting to stay between them , the ghouls of Los were friendly and showed great hospitality towards human strangers , allowing them to trade , and thus to survive . But a local civil war in the Secret Vault caused major damage to the Vault . The people of the Vault were divided and some , blocked because of the damage , or wanting to leave the vault , joined the surface with weapons and the city of Los , conducted by , the old security officer of the Secret Vault . Once on the surface , Blake formed the Church of the Lost , giving themselves a holy mission to protect people against the Secret Vault , as they consider it to hold an evil inside , that should never be released , and he took control of the city . After that , the Church of the Lost incorporated a sizeable portion of the old ghouls of Los to reinforce their newly created frenetic army . Now the city included those not part of the Church of the Lost , the first inhabitants of Los and some who came from the Secret Vault , who were friendly towards all . Those of the Church of the Lost controlled the city and killed or captured people for their bloody rituals or to interrogate them . Los then accepted only ghouls . Those who were friendly lived on the western and eastern part of the city ' s bridge . Important friendly ghouls here are an old engineer of the Secret Vault - Giese , a merchant Hieronymous and for a moment , an old traveler who comes from The Hub - Harold . Another friendly ghoul and a merchant , Salieri , is found nearby , in the docks . Also , the ghouls of Los manage a Gladiator Pit , an arena where anyone could fight for money and the crowd ' s entertainment . Everything changes again in Los when an army of Super Mutants , led by Attis , attacks the city . They quickly make their way to the only remaining entrance to the Vault and take it over , leaving only few of their soldiers to protect the entrance from raging ghoul fanatics of the Church of the Lost . Some time later , a group of Brotherhood of Steel Paladins arrive , lead by Rhombus , aiming to battle Attis ' s army . They were stuck between the Church of the Lost and Super Mutants soldiers , and only Rhombus survived , having been captured by Blake . Much later , the Initiate , with information from the Vault Dweller , finds the city . He liberates Rhombus , kills Blake and comes to fight his way through the Secret Vault . Inside , he activated the self - destruction sequence and the explosion wiped out city ruins on the other side of the Bridge of Los . As it ' s seen in " Fallout 2 " , the Initiate helped Harold to recover its members which prevented him from leaving Los , and he managed to leave the city before its destruction and to go to Gecko . Appearances . Los appears only in " " . Behind the scenes . According to numerous informations and indices in the and in - game , the only possible city for Los is Los Ybanez .