What do you call a room or building that only serves as the entrance to the main building, specifically in retail outlets like Walmart?

I’ve supplied a picture of precisely what I’m referring to in case my description within the title was complicated or too muddled

https://preview.redd.it/7l8cm6e196ed1.jpg?width=1839&format=pjpg&auto=webp&s=d701dd45b2ecb3153ed91a74cb5daea9f381ce3e

The blue circles are what I’m referring to