Tuesday is the big public opening day for Harvey Milk Terminal One, which opens its first gates to travelers after a two-year, $2.4 billion construction process. Nine of an eventual 25 gates are now open, along with a new boarding area and a tribute wall to Harvey Milk himself.

Only one half of the new terminal is opening, as the airport now plans to close and demolish a set of temporary gates that were in use by Southwest Airlines during construction. As SFGate reports, the first flight to leave from the new terminal this morning was a Southwest's flight 2293 to Las Vegas at 5:35 a.m. today. There are also two dedicated and one shared gate in the new terminal being used by JetBlue, whose 6:40 a.m. flight to JFK was the second to leave today.

And as airport officials and terminal designers explain in the video below, the Harvey Milk history wall is temporary, and when the next set of gates and larger T1 Center opens in March 2020, portions of the history wall will be moved into a permanent "inglenook," along with several other exhibits.

The planned "inglenook" for the Milk history materials. Rendering via SFO

"I was not expecting to see the museum-like feel walking through there," traveler Brian Martins tells NBC Bay Area. "Being a history teacher, I was pretty impressed in what I saw. And it was very calming to walk out of the plane into that setting."

As you may recall, there was initial talk of renaming the entire airport after Harvey Milk, but a ballot measure to make this happen never got off the ground. The Board of Supervisors and then mayor Ed Lee compromised in 2013 and decided to name a terminal after the slain, pioneering gay supervisor.

Other impressive aspects include several large public art pieces like the one below, and a grand oculus skylight, also shown below.

Photo: SFO

Photo: SFO

The airport says, with the new terminal, it "will once again set a new standard for the airport experience, making air travel less stressful, more entertaining, and more engaging than ever before!"

The portion of the terminal that is open is known as Boarding Area B, which will ultimately have 18 gates which also be used by American Airlines, Hawaiian Airlines, Frontier Airlines and Sun Country Airlines. The entire new portion of the terminal will have 25 gates, and American is expected to move its flights over to the terminal next March, when the next phase opens. Construction on the entire terminal, including connections to Delta's Boarding Area C (which is remaining as-is), and a walkway to the International terminal, will be completed by 2023. Currently, travelers must exit and re-enter to pass between the Delta boarding area, and the new part of Terminal 1.