In the town or city where one lives; in the town or city being referenced.
He'll be in town next week for business.
Tell everyone I'll be in town for a few days.
They definitely make the best burgers in town.
Lots of new businesses are opening up in town.
(as traditionally used in the environs of London, England, sometimes written 'in Town') In London, especially central London.
(informal) Present; making an appearance.
Source: en.wiktionary.orgWhen the biggest, richest, glassiest buildings in town are the banks, you know that town's in trouble. Edward Abbey
Hain't we got all the fools in town on our side And hain't that a big enough majority in any town. Mark Twain
Actors always have to fight for the good parts. There are so few good roles written for women each year, and when one is written like this every actress in town covets the role. Halle Berry
That is fashionable in town is never prohibited. Swahili Proverb
The servant wench that has a mother in town swoons seven times a day. Spanish Proverb
The dog that has its bitch in town never barks well. Spanish Proverb