- In mathematics, the empty set is the unique set having no elements; its size or cardinality (count of elements in a set) is zero. Some axiomatic set theories ensure that the empty set exists by including an axiom of empty set, while in other theories, its existence can be deduced. Many possible properties of sets are vacuously true for the empty set.
- Seattle Center (Wikipedia)
Seattle Center is an arts, educational, tourism and entertainment center in Seattle, Washington, United States. Spanning an area of 74 acres (30 ha), it was originally built for the 1962 World’s Fair. Its landmark feature is the 605 ft (184 m) tall Space Needle, which at the time of its completion was the tallest building west of the Mississippi River. Seattle Center is located just north of Belltown in the Uptown neighborhood.