I don't even understand how you can make a topographical (with elevations) map without aerial photography.

They used triangulation. Here is a simple way to do it. Stand across the street from a power pole or street light. Have an assistant stand next to the pole.

Hold a broom handle vertically at arms length. Aim at the base of the pole with the hand griping the stick & the tip of the handle with the top of the pole. Keeping your arm outstretched, rotate the handle parallel with the curb. Instruct your helper to step along the curb or sidewalk until you sight them along the tip of the handle.

You & your helper will be standing on the hypotenuse of a right triangle. The distance between your helper & the pole is the height of the pole. If you know the length of any one of the sides, you also know the length of the other two. Congrats, you are now a Roman engineer.

A right triangle is 3X4X5. The Egyptians used that fact to lay out their monumental constructions with exquisite accuracy. Military engineers used that simple triangulation technique for millennia. By the Civil War, surveying equipment was quite sophisticated & not dependent on right triangles.

This is the same principle that is used to find latitude. A triangle drawn with an imaginary line along the earth’s axis to the North Star & to your position tells you where you are in relation to the celestial North Pole. Standing on the pole, your sextant will be vertical, i. e. 90 degrees. Every step southward increases the angle proportionally.

West Point officers were trained to use theodolites & triangulation to chart very accurate mapping points. Connect the dots & you have a map. Triangulation in both vertical & horizontal orientation was & is the key to map making & navigation. It is what makes GPS possible.