KSTP is the ICAO code for Saint Paul Downtown Holman Field (IATA STP), located in Saint Paul, MN.
St. Paul Downtown Airport, also known as Holman Field, is an airport just across the Mississippi River from downtown Saint Paul, Minnesota. It is one of several reliever airports in the Twin Cities operated by the Metropolitan Airports Commission. The airport has three runways and serves aircraft operated by corporations in the local area, a flight training school and the Minnesota Army National Guard aviation unit, as well as transient general aviation aircraft.
Excerpted from Wikipedia, available under the Creative Commons Attribution-ShareAlike License.