A hallucination is a perception in the absence of external stimulus that has qualities of real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space.
Construction begins on Poland's tallest tower by Foster + Partners. Work has started on a 310-metre-high Warsaw skyscraper by Foster + Partners, expected to become the tallest building in Poland. The Varso Tower, or Warsaw Tower, is now under construction on a brownfield site next to the Warszawa Centralna railway station, with completion slated for 2020.
The world's tallest artificial structure is the 829.8 m (2,722 ft) tall Burj Khalifa in Dubai, United Arab Emirates. The building gained the official title of  Tallest Building in the World  at its opening on January 4, 2010. It is followed by the Tokyo Skytree, as the tallest tower, and the KVLY-TV mast.