"I go in into the tall building to the engineer and we chat."

Translation: Bemegyek a magas épületbe a mérnökhöz és beszélgetünk.

[Benjiii1989]

I noticed the "ö" when "to" means talking to someone (mernökhöz, nőhöz). Does "hoz" change to "höz" if we are talking to someone ?

[jsiehler]

No, it's just vowel harmony. The same ending takes three different forms: -hoz for back vowel words, and either -hez or -höz for front-vowel words.