From Longman Business Dictionary
downtowndown·town /ˌdaʊnˈtaʊn◂/ adjectiveadj [only before a noun] American EnglishAmEPROPERTY the downtown area of a city is the main business district where many shops and offices are locatedWe have about 100 personnel in our downtown San Diego office.
—downtown adverbadvI went downtown to open up the store.