
Foyer of the United Earth Embassy on Vulcan
A lobby or foyer was a large open area, usually on the first floor of a structure, that lead to other areas such as elevators and doors.
In 1996, Tuvok asked Rain Robinson how to get back to the lobby at the Griffith Observatory. She responded that he should "go right down the hall, take a left at Mars, right at Halley's Comet and then just keep going straight ahead past the soda machine." (VOY: "Future's End")
In 2152, while spending time with Jonathan Archer on Risa, Keyla declined to point out her planet in the sky, giving the excuse that she had a bad sense of direction and citing the fact that she'd gotten lost coming back from the lobby. Archer joked that he saw how that could happen, as it was "at least a hundred meters from here." (ENT: "Two Days and Two Nights")
The foyer of the United Earth Embassy on Vulcan was located in section A-01 of the facility. It was destroyed in an attack on the embassy in 2154. (ENT: "The Forge")

The lobby of the USS Enterprise

The damaged lobby of the USS Enterprise
In the alternate reality, the USS Enterprise had a lobby ascending to a dome at the top of the ship's primary hull. Walkways allowed crew members to cross the lobby on each deck. James T. Kirk and Montgomery Scott held onto these when the ship fell to Earth in 2259. (Star Trek Into Darkness, Star Trek Beyond)
In 2365, William T. Riker sent Worf and Data to the lobby of the Hotel Royale. (TNG: "The Royale")
In 2366, Jean-Luc Picard promised to meet Vash in fifteen minutes in the lobby of a resort they were staying in on Risa, just before they set out to find the Tox Uthat. (TNG: "Captain's Holiday")