A landmark is something that stands out in a landscape and helps people know where they are. If you're walking through an unfamiliar neighborhood and someone tells you to “turn left at the big red barn,” that barn is a landmark. Sailors once navigated by landmarks along the coast, using distinctive rocks, lighthouses, or hillsides to guide their ships safely.

The word also describes buildings or places that are famous or historically important. The Statue of Liberty is a landmark of New York City. The Golden Gate Bridge is a San Francisco landmark. These structures are so significant that they've become symbols of their cities, appearing on postcards and in movies. Many landmarks are protected by law so they can't be torn down or drastically changed.

Beyond physical places, landmark can describe anything that marks an important moment or achievement. A landmark decision by the Supreme Court might change how laws work across the country. A scientist's landmark discovery might open up entirely new fields of research. When you accomplish something that changes everything that comes after it, you've reached a landmark moment, like a hiker reaching a peak that lets them see the whole territory they've covered and the new landscape ahead.