Phuket's old town is the most architecturally interesting part of the island, a compact grid of streets centered on Thalang Road where Sino-Portuguese shophouses from the late 19th and early 20th century have been carefully restored. The facades combine Mediterranean arched colonnades at street level with Chinese lattice screens and tilework above — an aesthetic particular to the tin-mining towns of the Malay Peninsula.
The best streets for walking are Thalang Road, Dibuk Road, and the sois (lanes) that connect them. Thalang Road is the most visited, lined with repurposed shophouses holding cafes, galleries, and small guesthouses. The side streets are quieter and often more rewarding — look for the active Chinese clan temples (joss sticks burning, red paper offerings), the old Chinese school buildings, and the occasional street mural. The whole area is small enough to explore on foot in a morning.