Perhaps the best-known landmark in KL is the Petronas Twin Towers, which for a while was the tallest building in the world; it's still the largest twin towers building. We showed up early to get tickets, as they only allow a limited number of people each day to go up into the skybridge, the bridge between the two buildings. Because the building is used for office space, visitors can't go any higher than the skybridge. You can read more about the towers at Wikipedia.
The type of visa that we have requires us to exit the country every 90 days, so for our first "visa run" we jumped at a chance to visit Kuala Lumpur, Malaysia, for a couple days. In summary, we loved it! KL (as it is known) is a large, modern, clean city. It has great public transportation, lots of things to see and do, and (due to its British heritage) many English-speakers! Everyone we met spoke at least passable English, which made it really easy to get around and get help; plus, the people we met were all very friendly. We would definitely go back to KL if we got a chance.