The basic rule I am taught with the superlative degree is to compare two or more things and if a noun takes the superlative degree, that's the highest among its similar kinds of things.
Superlative (in grammar): Of, relating to, or being the extreme degree of comparison of an adjective or adverb, as in best or brightest.
A basic example:
In my school, Tom is a tall boy, Dick is taller, and Harry is the tallest. Undoubtedly Harry is the tallest in the school.
Taipei Tower is tall, CN Tower is taller and Burj Khalifa is the tallest building in the world.
Now the question:
How there can be one of the -est in any case? If there is something more than one, it doesn't take superlative. The CN Tower and Burj are certainly not two tallest buildings in any case, are they?
Consider 500 pupils in that schools. May I say Tom is one of the tallest boys?
Considering 10 tall buildings in the world, may I say WFC is one of the tallest buildings?
There should be The List of Top Tall (and not Tallest) Buildings in the World. Because if it's tallest, it's ONE. Can it be more than one?
Note: This is a general question and goes the same with one of my best friends; one of the biggest industries in this state; one of the fastest cars and so on!