Your sentence
C'est+la+plus+belle+ville+du+monde.
Words in this sentence
être
to be; to be located; to be situated; to denote time, day, or date; used to form compound tenses and structures, such as the perfect and pluperfect; certain intransitive verbs that indicate movement or a change of state (see the full list); all reflexive verbs; the passive voice
Verb
plus
used to express the comparative and superlative of a following adjective or adverb; more, -er (comparative); most, -est (superlative); more, most (to a greater / the greatest extent); the more ...; more (a greater amount); [with de] more of a following noun; [with de or que] more than a following number or fraction; more, in addition; plus; …
Adverb
du
contraction of de + le, literally “of the”