Earning its nickname from the large number of red brick buildings comprising the area, Heimdallr has served as the nexus of the nation since the Orbal Revolution. The city's seventeen districts are connected through both railways and Orbal bus routes, creating a vast transportation network.
The city also serves as the seat of the Imperial Government, with Valflame Palace, official residence of the Arnor dynasty and Imperial Chancellor, situated north of Dreichels Plaza.
Heimdallr serves as the field study location during Chapter 4: A Midsummer's Revels, between August 24th and August 26th. Due to the immense size of the city, Heimdallr was visited by both Class VII groups. Once they arrived, they undertook tasks assigned to them by Machias' father, Carl Regnitz.
On the evening of the second day, Sara assembles a Class VII meeting at the station and reveals that the Imperial Liberation Front will be making their move on the festival. As a preventative measure against them, she assigns Class VII as a festival security detail.
In the early morning on the third day, Michael Gideon gathered laborers from the Pier to a meeting to discuss the start of their comprehensive, city-wide attack. Hours later, Elise Schwarzer and Alfin Reise Arnor head for the scheduled summer festival public event at Mater Park.
At the climax of the summer festival, Gideon and his men attack the neighboring districts, sabotage city utilities, and sever communication lines. This effectively throws the city security forces into total confusion. Under the cover of the ensuing chaos, a group of Imperial Liberation Front members led by Gideon successfully capture Princess Alfin and Elise at the Crystal Garden.
Class VII's Group A, after successfully seeing through the chaos, head to Mater Park to stop Gideon, only to be impeded by two Sharkodiles. Group A defeats the summoned monsters and proceeds into an underground passage, chasing after Gideon's men. At the end of the passage, they reach the Heimdallr Catacombs, where they corner Gideon. Using his demonic flute, Gideon reanimates Zoro-Agruga's skeletal remains in a last ditch effort to defeat Class VII. After defeating the reanimated skeleton, Rean shatters Gideon's demonic flute. However, as Gideon is driven into a corner, he and his men are rescued by Comrades V and S, with Comrade C in tow. While Machias Regnitz and Elliot Craig attended to Alfin and Elise, Rean heads up a team to battle Comrade C, only to be outmaneuvered by the leader of the terrorist organization. As a last resort, C triggered a cave-in in which allowed him and his team escape. Group A, along with Alfin and Elise, survive unharmed, and they make it back safely to Heimdallr.
After surviving the terrorist attack, Class VII is personally commended for their heroic actions at Valflame Palace. It is here that they meet Chancellor Giliath Osborne for the first time.
As a result of Crossbell's aggressiveness and the destruction of Garrelia Fortress, Osborne held a speech at Driechel's Plaza on October 30th. However, partway through his speech, he was shot by C, who is revealed to be Crow Armbrust in disguise. After the shot, the Noble Alliance staged a coup de'tat, utilizing Panzer Soldats to successfully seize control of the capital for the Noble Alliance.
On December 31st, the Imperial Army's 3rd and 4th Armored Divisions led an assault in an effort to retake the capital. While the bulk of the Noble Alliance's forces were distracted, the Courageous flies directly towards the Karel Imperial Villa on the outskirts of Heimdallr, to the west. There, Class VII successfully rescued Elise Schwarzer, Carl Regnitz, Emperor Eugent III and Empress Priscilla. However, due to the efforts of Vita Clotilde, Valflame Palace is consumed by the enormous Infernal Castle summoned from the depths below Heimdallr. Upon the defeat of the Vermillion Apocalypse, the Infernal Castle disappeared from Heimdallr.
Heimdallr consists of sixteen districts. The ones mentioned are listed below in alphabetical order:
- Alto Street: A residential area in the east of Heimdallr, featuring an unoccupied former Imperial Bracer branch. Elliot Craig lives here.
- Garnier District: A high-class shopping centre in the east of Heimdallr. The famous Heimdallr Opera House is also located here.
- Heimdallr Port: The harbour district of Heimdallr.
- Mater Park: A major city park. The Crystal Garden is situated here.
- Ost District: Heimdallr's old town, where the price of the land is relatively low. Machias Regnitz lives here.
- Sankt District: Sankt District is situated in the northwest of Heimdallr. Heimdallr's Grand Cathedral and several embassies are located here. The St. Astraia's Girls School is attended by girls from noble backgrounds, such as Princess Alfin Reise Arnor and Elise Schwarzer.
- Vainqueur Street: A large street in central Heimdallr connecting its Central Station to the Valflame Palace in the north of Heimdallr.
- Vesta Street: A large street on the west side of Heimdallr. It features the ruins of a former Imperial Bracer branch.
- The city's districts are derived from multiple German words: "Garnier" means dunnage, "Ost" stands for east, and "Sankt" means saint
- The city is named after a Norse god of the same name.