The United Earth Embassy was United Earth's permanent diplomatic mission on Vulcan during the 22nd century. The United Earth Embassy was administered through the United Earth Diplomatic Corps, with officers from the United Starfleet serving in numerous operational and support positions.
In 2154, Maxwell Forrest and Vulcan Ambassador Soval visited the Embassy to discuss the preliminary stages of joint missions between Earth Starfleet and the Vulcan High Command. In the course of this discussion, the embassy was bombed and badly damaged, killing at least forty-three people – including Admiral Forrest. The bombing was originally blamed on the Syrrannite movement, which the High Command characterized as a terrorist organization. It was later found that the embassy had been bombed by agents of Administrator V'Las, who sought to publicly discredit pacifist movements such as the Syrrannites as part of his plot to launch a preemptive invasion of the Andorian Empire. (ENT: "The Forge", "Awakening", "Kir'Shara")
The exterior of the United Earth Embassy was designed by senior illustrator John Eaves. He commented of the embassy, "It really had to stand out so it went into a bright white surface color with a lot of cool architectural lighting to punch it out from the sea of red and purple that made up the Vulcan palette. Hard faceted and angular lines would also make for a good contrast against the very curvy organic lines all around the Embassy." 
Presumably, this embassy served as the primary workplace for the United Earth Ambassador to Vulcan.
The script and production report for the Star Trek: Enterprise episode "The Forge" at wbm establish that the United Earth Embassy was in Shi'Kahr. This intention was also included at the bottom of a concept illustration that John Eaves created for the embassy (artwork that can be viewed here).