To my mind the most striking and remarkable thing about Colombo is its trees. While generally the town is short on the things that make it friendly towards humans, like pavements (which only exist alongside the main roads) and parks, there is always an abundance of wonderful trees.
Anyhow, one tree of note is found on R G Senanayake Mawatha, aka Gregory's Street (and as you can see why it has a certain homely feel to me - it is a broad, fairly quiet street with a pavement, it is lined with trees and even has red pillar boxes).
