If you have two buildings 4km apart (about the length of Central Park), that’s about 1/10,000 of an earth circumference so 0.036° change in ‘up’. If the buildings are 300m tall, 300*sin(0.036°) = 0.188m

That’s less than those buildings are probably expected to sway in a strong wind, but probably outside the tolerances for modern construction so theoretically measurable as an average deviation.