This is the 138th most frequent Romanian word.
bucurești
București is the Romanian name for Bucharest, the capital city of Romania.
Here, 'București' is used as a proper noun representing the capital city of Romania, used in a locative context.
Locuiesc în București și îmi place foarte mult orașul.
I live in Bucharest and I like the city very much.
In this sentence, 'București' is again a proper noun, presented as an interesting travel destination.
Îți recomand să vizitezi București pentru arhitectura lui impresionantă.
I recommend that you visit Bucharest for its impressive architecture.
'București' in this context specifies the place where the friend resides and the event takes place.