What is the main measurement that a mason seeks to find when squaring a building?

When squaring a building, the primary measurement that a mason needs to determine is the diagonal measurement. This method relies on creating a right angle between the walls and ensures that the structure is perfectly square. To check for squareness, the mason often utilizes the Pythagorean theorem, which states that in a right triangle, the square of the length of the hypotenuse (the diagonal measurement) is equal to the sum of the squares of the other two sides. By measuring the diagonals of the building plot, the mason can verify that both diagonals are equal; this indicates that the corners are at right angles and that the layout is square. Thus, focusing on diagonal measurement is crucial for ensuring accuracy and stability in the construction process.