Simplify the following text for a Grade 9 native English-speaking person.
Original: At 298 metres , or 978 feet ( 355 metres with antenna included ) , it is Canada 's tallest skyscraper and the eleventh tallest building in North America .
Simplified: At 289.9 m , it is Canada 's tallest skyscraper and the eleventh tallest building in North America , and the 68th tallest in the world .