Where are leads usually built to establish proper height and provide a place to attach the mason's line?

Leads are primarily built at each corner of a masonry project to establish the proper height and to provide a secure place to attach the mason's line. This technique is essential for ensuring that the walls are straight and level throughout the construction process. By placing leads at the corners, the mason can easily check the alignment and height of the walls as they progress, which helps maintain a consistent and accurate structure.

Building leads at corners allows for better visibility and access when installing the mason's line, which acts as a guide for laying the other masonry units. This practice helps in achieving uniformity across the entire wall, ensuring that the structure is not only aesthetically pleasing but also structurally sound. In contrast, leads placed in the middle of walls or along the edges would not effectively serve these purposes, as they would not provide the same level of support for setting the lines or ensure proper alignment of the masonry work.