The Old City is a major destination for travelers, as it's home to opulent temples like Wat Po and Wat Phra Kaew. Across the river is Thonburi, a mostly residential neighborhood, where you can find Wat Arun. At the northern tip of the Old City is Banglamphu, one of Bangkok's older residential neighborhoods. It's best known now for Khao San Road, a backpacker hangout, though the neighborhood has much more to offer, especially when it comes to street food. North of Banglamphu is Dusit, the royal district since the days of Rama V.
East of the Old City is Chinatown, a labyrinth of streets with restaurants, shops, and warehouses. Farther down the Chao Phraya River is bustling Silom Road, one of the city's major commercial districts. Patpong, the city's most famous of several red-light districts, is also here. Bang Rak is home to some of the city's leading hotels: the Mandarin Oriental, the Peninsula, the Royal Orchid Sheraton, and the Shangri-La. To the north of Rama IV Road is Bangkok's largest green area, Lumphini Park.
Continue north and you reach Sukhumvit Road, once a residential area. More recently, Thong Lor, farther east along Sukhumvit, has become the "in" neighborhood for those want to see and be seen. The Nana and Asok areas of Sukhumvit are now home to the even busier red-light entertainment districts (Nana and Soi Cowboy) than Patpong.