There are cities that ask you to look up. New York, of course. Tokyo, Paris, London. Then there are the cities that invite you to look out. The vistas are the party. Los Angeles is a looking-out city. And when you do, what you see are trees.

The trees of Los Angeles may well be the most underrated reason to visit. “This is one of the most densely populated, diverse urban forests in the world,” said Bryan Vejar, the senior manager of arboricultural training and education at TreePeople, the oldest environmental nonprofit based in Southern California. (TreePeople has planted three million trees since it started 50 years ago.) “We have nearly 500 different species of trees in greater Los Angeles,” said Mr. Vejar.

The trees of Los Angeles are as varied and storied as the city itself and touring them is the cheapest way to take in its charms.

“Every neighborhood treats their trees differently,” said Nick Araya, a master arborist and founder of TreeCareLA, a tree management company. “In Laurel Canyon, it feels like the trees are in charge. But then there are places that are much more manicured. It’s very rare that a tree will start growing in Beverly Hills and be allowed to stay.”