sentence: Lighthouses are built on the coast of an ocean or lake.
sentences_before: A 'lighthouse' is a tall building that has a light near the top.
sentences_after: The lighthouse protects ships from crashing into shore by sending the light out towards the sea. The light usually turns in a circle so that ships see a flashing light. The light is usually covered by a Fresnel lens. This lens enables the light to travel a far distance.
concept_name: lighthouse
headings: Lighthouse
categories: Buildings and structures Navigation Water transportation