Perhaps you mean The Forum, but it's more trapezoidal than rectangular.
The open central court inside of a house in ancient Rome was called an "atrium".
The ancient Romans called any large open area a campus. An example is the Campus Martius at Rome.
open the bonnet on your car, look for a large black plastic box, that is it. on diesels usually rectangular, petrols circular i believe,
A large rectangular Roman administrative building is called a "basilica." These structures served various functions, including as courts of law and public meeting places, characterized by their long, open interior spaces and often featuring an apse at one or both ends. The design of basilicas influenced later architectural styles, particularly in early Christian churches.
Large open economy.
There will be a small rectangular button underneath your opening. Push it.
No, it is an open border.
1 rectangular face (the square base) and 4 triangular faces. Justin Dip(Math) Open
The center of ancient Rome was the Forum, the open plaza and marketplace around which the government buildings were located.
A central glass-roofed hall is commonly referred to as an atrium. It is a large open space within a building that is often surrounded by multiple levels and designed to allow natural light to illuminate the interior.
about 10ad
You cannot make a solid shape with 5 rectangular sides. You can make an open rectangular box, leaving off the last side. You can make a rectangular box (like a cube, but with possibly unequal sides) with 6 rectangles. You can make a rectangular pyramid with one rectangle and four triangles.