an agora
The Agora is an open area below the Acropolis in ancient Greek cities that served as a marketplace and a hub for political, social, and cultural activities. It was a focal point of ancient Greek city-states and typically included temples, government buildings, and spaces for public gatherings.
Outside:the eaves(Have you heard of "eavesdropping", standing under the eaves and listening secretly through open windows?)Inside:ceiling
Plain
an open area
The open deck of a ship is called the weather deck.
If the cable is broke you can crawl under and manually release the hood. It isn't too bad, the area is open and visible from under the car.
When a fracture is associated with a laceration or cut in the area of the fracture, it is called an open fracture
The ancient Romans called any large open area a campus. An example is the Campus Martius at Rome.
An Outlet. I'm pretty sure!
I don't think there is a particular name for the area. It is just a passageway to allow people to walk abaft (behind) the bridge, it would be called a companionway. If it is larger, then is just open space or open deck area within the bridge deck.
Flat open land is called a plain. A plain is a flat area with few trees. They can occur as lowlands and at the bottom of valleys, but can also be on plateaus or uplands at high elevations.
Cargo area.