Generally, the "red carpet" (which isn't always red) will be out on the sidewalk or on the closed-off street. From there, most attendees walk through this entrance. At all other times, this is just another part of the mall, with a few shops and the escalators to the parking garage.
Here's how the outside of the theater and Hollywood Boulevard looked during the Oscars in 2014. The tent you see on the far right is a portion of what they'd use for the whole block. So that tent, but stretched to cover all the way to the entrance. Beyond, too, if the TCL theater (to the left of this image) is used as well.
Sometimes check-in for an event is here, behind the stairs. Find your name, get your tickets, and pass through a metal detector to get inside. Other times, like for the Force Awakens premiere, check-in was down the block. So I was able to just walk up the stairs, hand over my phone, then pass through a metal detector.
The special VIP room off the main lobby. A 120-inch Vizio TV and a full Atmos surround system entertain the guests. The doors in the far wall go to the hallways that weave under and around the theater to get people back, and eventually on, stage.
To me, the most fascinating aspect was how much smaller the theater seems from the stage, compared to when sitting in the audience. One of the theater employees that was guiding my tour explained that part of that is because the mezzanines are stacked vertically, instead of raked backward. Also, there's "only" seating for 3,400, which is small compared to the size of the stage.
Sometimes the crew only has a few hours to convert the theater from one use to another. Here you can see them setting up for a premiere by dropping the screen from its storage slot, installing it, and mounting all the speakers.
The area directly in front of the stage is height-adjustable. Here it has additional chairs used during some events. During the Oscars, it descends to house the orchestra. It can also be raised, as it is during premieres, since sitting up here would be way to close to the screen for comfort.
Everything in the theater was designed with TV in mind. The seats, for example, aren't a single shade, but maroon with a textured black striping, which shows up better and has more "depth" to the camera's eye.
So this is really cool. The projectors used during premieres don't live at the theater. They're brought in for the show. However, the laser light sources for said projectors, are semipermanently mounted. They hide below the projection booth. And if you know where to look...
Built higher than Dolby would usually prefer, the company had to make do with the layout it inherited when it took over the naming rights in 2012. The angle down to the screen isn't ideal, but I doubt anyone but Dolby staff would notice.
So next time you're at the Academy Awards, or watching them or any of the countless other TV shows recorded here, you'll now have a better idea what the Dolby Theater truly looks like, minus all the glitz and glitter (i.e., still pretty cool).