the usage of "one of the most"

You ask
If there are only two hotels....can we say "ABC is one of the most famous hotel in UK"
No.for several reasons:
1: the example phrase should be most famous hotels (plural) in (the) UK.
2; again using your example ABC must be either the most famous hotel in the UK,or the second most famous hotel in the UK.
3: most famous should not and would not ever be used in good English, when there are only two to judge.