Colombo is most visitors' first stop off the plane — a coastal capital where colonial-era buildings in Fort sit blocks from glass towers, and the Galle Face Green promenade fills with kite-flyers at sunset. It's less a single sight than a base for exploring the rest of the west coast.
A wide seafront promenade in the heart of the city, popular at sunset for kite-flying, street food carts and sea views.
Colonial-era clock towers and banks in Fort give way to Pettah's dense, chaotic bazaar streets just a few minutes' walk away.
A working Buddhist temple blending Sri Lankan, Thai and Chinese architecture, with an eclectic museum of donated artefacts on site.
Colombo pairs naturally with a Colombo street food tour or a half-day trip to Kelaniya Raja Maha Vihara before heading further afield. For general background, see Colombo on Wikipedia.