Bangkok is a large, sprawling city. Administratively it is split up into 50 khet (districts), but these are rarely used in practice and the visitor will find the conceptual division below more useful. Sukhumvit and thhe long Sukhumvit road, and afterwards changing name to Ploenchit Rd and Rama I Rd going west, is Bangkok's modern commercial core, full of glitzy malls and hotels. The Skytrain intersection at Siam Square is the closest thing Bangkok has to a center. Silom,  to the south of Sukhumvit, the area around Silom Rd and Sathorn Rd is Thailand's sober financial center by day, but Bangkok's primary party district by night when quarters like the infamous Patpong come alive. Rattanakosin, Between the river and Sukhumvit lies the densely packed "Old Bangkok", home to Bangkok's best-known wats. Yaowarat (Chinatown) and sights around the Chao Phraya River are also included here. Bangkok's backpacker mecca Khao San Rd. and the surrounding district of Banglamphu are located on the northern part of Rattanakosin. Thonburi is the quieter west bank of the Chao Phraya River, with many small canals and some offbeat attractions. Phahonyothin  and the area around Phahonyothin Road and Viphavadi Rangsit Road is best known for the Chatuchak Weekend Market and Don Muang Airport.  Ratchadaphisek, the district north of Sukhumvit centered around Ratchadaphisek Rd (part of which is called Asoke) and reaching from Phetchaburi Rd to Lat Phrao is the area that has really opened up recently as the new metro line follows Ratchadaphisek road.