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. Even in the modern day, it kept its traditional cityscape thanks to a Landscape Act, which prohibits the construction of tall buildings.
Carriages were the standard in Heimdallr until approximately S.1180 when the orbal tram network was introduced. The city's seventeen districts are connected through both railways and orbal bus routes, creating a vast transportation network. In the present day Heimdallr, however, traffic congestion is commonplace and trams are regularly 10 to 15 minutes delayed.
Heimdallr serves as the field study location during Chapter 4: "A Midsummer's Revels" between August 24 and August 26. 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 Governor Carl Regnitz, the father of Class VII student Machias 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, ILF member Michael Gideon gathered labourers from the Heimdallr Port to a meeting to discuss the start of their comprehensive, city-wide attack. Hours later, Princess Alfin Reise Arnor and her friend Elise Schwarzer 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 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 outmanoeuvred by the leader of the terrorist organisation. As a last resort, C triggers a cave-in in which allows 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 aggression and the destruction of Garrelia Fortress, Osborne holds a speech at Dreichels Plaza on October 30. 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 stages a coup d'etat, utilising Panzer Soldats to successfully seize control of the capital for the Noble Alliance.
On December 31, the Imperial Army's 3rd and 4th Armored Division 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 rescues 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 disappears from Heimdallr.
Heimdallr consists of sixteen districts. It is unknown what classifies as a district in Hemdallr. The following list features Heimdallr areas (districts) mentioned in the games alphabetical order:
- Alto Street
- Central Station
- Dreichels Plaza (Valflame Palace)
- Garnier District
- Heimdallr Port
- Leica District
- Mater Park
- Ost District
- Racetrack Plaza
- Sankt District
- Vainqueur Street
- Vesta Street
- 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 the Norse god of the same name.