A district in north-central Kuala Lumpur split by main avenue Jalan Tuanku Abdul Rahman, there is quite an array of local foods and hawker streets and a distinct nightlife area, making it an easy place to navigate once you know what you want to do.
Jalan Doraisamy (otherwise known as "heritage row") is your party destination, located just off of Jalan Sultan Ismail. The average age is in their early 20's, so be prepared for the type of intoxication that normally accompanies party-goers of this age; that aside, you'll find a ton of nightclubs pumping great dance music that bring in quality DJ talent (Gosh Club, Maison, Sixty3, the list goes on...).
At the northern end of the district is the Chow Kit neighborhood, whose central landmark is the Kuala Lumpur hospital. Explore the streets just south of the hospital for a great selection of predominantly Malaysian restaurants, although you'll find a lot of cheap, quality choices just off of Jalan Tuanku Abdul Rahman along its full length. Establishments of note include excellent seafood at Restoran Lala (Jalan Raja Abdullah), the fittingly named BBQ Restaurant on Jalan Ipoh, Malaysian favorite Selera Ramai 1 Ikan Singgang (Medan Selera), and great nasi kandar at Restoran Kudu bin Abdul (Jalan Tuanku Abdul Rahman).
For the best collection of hawker stalls in the district, Jalan Haji Hussein in Chow Kit is the place to be (also just south of the hospital).