How is the height (of a city or mountain) measured from sea level especially if it's far inland?

Answer 1

The USCGS used a series of benchmarks, each visible from a number of others. The elevations thus obtained were quite accurate.

Answer 2

the best is measured utilising a the pressure distinction in between the sea aspect and an section on the better altitude the version of pressure is given by technique of (pgh) p is the density of air, g is the acceleration through gravity, h is the version in good