Like Tokyo's Ginza, Ximending is the ultraconsumerist heart of Taipei's mainstream youth culture. This eight-branched intersection dates from the Japanese era and is now chock-full of shops selling fashion, fast food, sneakers, sunglasses, scarves, Sanrio, Sony and spaghetti. If it's young and trendy, it's here.
The pedestrian streets northwest of the main intersection (between Chengdu Rd and Wuchang St) is more or less the epicentre, but for the full Ximending experience you'll really want to explore the smaller alleys. It's here you'll find the edgier side of Taiwan's youth culture, the places they hang and the stores in which they work and shop.
Take the THSR to Taipei Station, and continue by MRT to Ximen Station.