Heimdall's Observatory was located just outside Asgard, at the edge of the Sea of Asgard, and was connected to the Rainbow Bridge. The Observatory generated and directed the Bifrost using the energy that ran through the Rainbow Bridge. From the Observatory, Heimdall commanded the Bifrost and looked over the Nine Realms and other regions of space. It was considered one of the most important places in all the Nine Realms.
During the Second Dark Elf Conflict, Heimdall committed treason in order to allow Thor, Loki and Jane Foster to escape to Svartalfheim. After Loki faked his death during a fight with the Dark Elves, he stripped Odin of his power, sending him to New York City and subsequently disguised himself as Odin, seizing the throne. As Odin, Loki charged Heimdall with treason, forcing Heimdall to abandon his post and flee. Loki then assigned Skurge to be the new gatekeeper, tasking with one important duty – to notify him if Thor ever returned.
Built on the outside of Asgard, Odin appointed Heimdall, who was gifted with enhanced senses, as its keeper.
Heimdall opened the Bifrost for Thor's friends when they journeyed to Midgard to bring back Thor. When Loki became regent after Odin falls into the Odinsleep, Heimdall was relieved of his duties as gatekeeper and his citizenship of Asgard was revoked by Loki, and was subsequently imprisoned in ice by the Casket of Ancient Winters. Loki travelled to Jotunheim and brought Laufey and two other Frost Giants to Asgard to assassinate Odin. The two Frost Giants were told to guard the Observatory and the frozen Heimdall. Hearing Thor's shouts to open the Bifrost, Heimdall managed to break free from the ice, slay the two Frost Giant sentries, and bring back Thor and his friends to Asgard. Loki then opened the Bifrost to destroy Jotunheim, but Thor fought him, and ended up breaking the Rainbow Bridge and the Observatory fell into the abyss of space. Loki then refused to accept his father's help and fell into the wormhole that the broken Observatory formed with the Bifrost.
Heimdall witnessed the uprising of the Marauders who sensed the absence of the Asgardians' presence and the Bifrost, as well as Frigga locating Loki and learning of his plans. Without a Bifrost to prevent the war, Odin sought out the Tesseract in order to use its energy to repair the Bridge and the Observatory. And so, he mustered dark energy to transport Thor to Earth. After Thor returned to Asgard with the Tesseract and Loki, Heimdall used the Tesseract's energy to repair the Observatory and once again was able to open the Bifrost, and Asgard's troops were sent across the Nine Realms to defeat the Marauders.
Thor visited Heimdall at the Observatory after the war to visit Jane Foster and to bring her to Asgard when they discovered the Aether in her. After the Dark Elves invaded Asgard, Odin ordered the Bifrost to be shut down. As part of Thor's plan, Heimdall summoned Odin and Tyr to the Observatory to distract them from Thor and Loki escaping Asgard. Afterwards, Thor returned to stay on Earth with Foster.
From the Observatory, Heimdall saw a Kree arrive on Earth and reported it; Sif was sent to investigate. Later, Sif called Heimdall so that she and the Kree named Vin-Tak could go to Asgard before sending him to Hala.
After the Avengers had succeeded in defeating Ultron, Thor called upon Heimdall to bring him back to Asgard so he could begin his search for the Infinity Stones. Unbeknownst to Thor, Loki had dethroned Odin as king and exiled Heimdall in act to ensure his reign over Asgard.
In the absence of Heimdall, Loki employed Skurge to work the Observatory, knowing a mere janitor would blindly follow orders without posing as a threat to his rule.
Return from Muspelheim
After Thor defeated Surtur, he returned to Asgard with his Crown to place in the Vault for safekeeping. Furthermore, Surtur had taunted Thor during the fight, informing him that Odin was no longer present on Asgard. Meanwhile, Skurge had been gleefully neglecting his duties, bringing two women and a large amount of his personal possessions from travels to the Observatory. Despite not answering Thor's calls for an uncomfortably long time as Thor was being chased by a Fire Dragon, Skurge eventually activated the Bifrost, declaring to the women that they were in for a treat. The Bifrost successfully brought Thor to Asgard as well as decapitate and transport the Fire Dragon's head as well, splattering the walls of the Observatory and its inhabitants with its blood.
After Thor discovered that Loki had been masquerading as Odin for quite some time, the two set out to Midgard to search for him. In addition, someone with command designated Fandral and Volstagg to guard the Observatory as well to cover for Skurge's incompetence and supervise the cleaning. After Odin's death mere hours later, Hela was freed from her imprisonment. She easily defeated Thor and shattered Mjolnir in Norway, to which Loki panicked and asked the Observatory to bring them back to Asgard, not thinking that Hela would grow exponentially in strength once she arrived there.
Volstagg answered the call, transporting all three of them. However, during the transit, both Thor and Loki were thrown out of the bridge, leaving Hela alone. Upon arriving, Volstagg demanded to know who Hela was and what had happened to Thor. In response, Hela coldly threw two Necroswords at Volstagg and Fandral, hardly giving them a chance to arm themselves with Volstagg's Axe and Fimbuldraugr. She quickly finished them off with two more Necroswords.
After witnessing the deaths of two of Asgard's finest, Skurge quickly knelt and declared himself simply the janitor. Hela told him he had good survival instincts, and offered him a job: her personal Executioner.
Heimdall Steals Hofund
Hela and Skurge would cross the Rainbow Bridge shortly after to confront the population of Asgard. Meanwhile, Heimdall had been watching from some distance, and managed to sneak into the Observatory unnoticed to steal Hofund, which would stop Hela from being able to transport herself to other realms until she recaptured it.
Desolation of Asgard
Although Heimdall's Observatory was within walking distance of the Battle of the Rainbow Bridge, no actual fighting took place inside the Observatory. It was destroyed along with the rest of Asgard by Surtur as Loki caused Ragnarök at Thor's behest to defeat Hela.
- The connector of the Bifrost and Rainbow Bridge, the Observatory converts the energy that flows through the Rainbow Bridge and generates the Bifrost portal with it.
- In Norse mythology, Heimdall has a golden hall named Himinbjorg located where the Bifrost meets heaven.