The Gateway Arch, also known as the Gateway to the West, is an integral part of the Jefferson National Expansion Memorial and the iconic image of St. Louis, Missouri. It was designed by Finnish-American architect Eero Saarinen and structural engineer Hannskarl Bandel in 1947. It stands 630 feet (192 m) tall, and is 630 feet (192 m) wide at its base, making it the tallest monument in the United States. Construction of the arch started on February 12, 1963 and was completed on October 28, 1965.
An air ionizer (or negative ion generator) is a device that uses high voltage to ionize (electrically charge) air molecules. Negative ions, or anions, are particles with one or more extra electrons, conferring a net negative charge to the particle. Cations are positive ions missing one or more electrons, resulting in a net positive charge. Most commercial air purifiers are designed to generate negative ions.
The Lincoln Building built in 1908 was an historic school building located off U.S. 281 in Carrington, North Dakota. On April 30, 1980, it was added to the National Register of Historic Places. Reportedly, it is scheduled to be torn down in June or July 2008.