Heimdall's Observatory is located just outside Asgard and is connected by the Rainbow Bridge. The Observatory generates and directs the Bifrost using the energy that runs through the Rainbow Bridge. From the Observatory, Heimdall commands the Bifrost and looks over the Nine Realms and other regions of space. It is considered one of the most important places in all the Nine Realms.
Thor and his companions traveled to it to journey to Jotunheim, and later Odin banished Thor from Asgard from within the Observatory. Later, 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after Odin falls into the Odinsleep, Heimdall was relieved of his duties as gatekeeper and his citizenship of Asgard was revoked by Loki, and was subsequently imprisoned in ice by the Casket of Ancient Winters.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 traveled 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 the Bifrost, Odin 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.
The Bifrost Bridge is a transit system used by Asgardians to travel to the various realms among the Nine Realms and numerous other planets. The Bifrost uses a powerful, rainbow-like energy drawn from the center of Asgard to create Wormhole-like portals that can instantaneously transport people and objects between realms, over light-years of distance with CL1000 ability. On other realms, the Bifrost appears as a brilliant beam of white light that shines down on its surface, often leaving behind a rune-like pattern burned into the ground. The beam of energy projected by the Bifrost is powerful enough to destroy a realm/planet if it is allowed to remain open long enough with CL1000 ability. Hofund, Heimdall's sword, is the key to activate the Bifrost Bridge.
