Biden arrived at about 3:15 p.m.

ET, and greeted an entourage that included former UN ambassador Andrew Young and Stacy Abrams.

Also spotted, per a pool report: Jeffrey Katzenberg, who is serving as campaign co-chair.

Joe Biden getting off Air Force One this afternoon.

Joe Biden getting off Air Force One this afternoon.MANDEL NGAN/AFP via Getty Images

Holocaust Museum’s Board

Trumps plane landed at about 5:30 p.m.

ET, and he waved and gave a fist sign to cheering supporters.

The candidates will face each other at 9 p.m.

Donald Trump and ABC News' Terry Moran

CNN’s spin room was set up in McCamish Pavilion, a Georgia Tech arena near the network’s studios, where the debate will take place.Photo by Andrew Harnik/Getty Images

ET, for a 90-minute debate that is hosted by CNN at their Atlanta studios.

The debate will begin live at 9 pm.

Among those spotted so far for Trump: Rep. Byron Donalds (R-FL).