Assuming the building is a regular rectangular prism, then we can just look at the scale. The building is 120 pixels tall and 20 pixels wide. The plot is 250 feet wide. 120 is 6 times larger than 20 so the assumed scale factor is 6. So 250 * 6 = 1500. The building should be 1500 feet tall.
The zoomed image is 6 times as tall as it is wide. Assuming that same ratio applies, and that the land measurement represents the building width, the height of the building will be ...
