Launch Complex 37B (LC-37B) is one of a pair of launch pads comprising LC-37 situated on Cape Canaveral Air Force Base. The other LC-37A was never actually used, indeed the USAF only ever refer to the Launch Complex as LC-37.
Construction of LC-37 started in 1959 and saw the first rocket launched in January 1964. This was the a Saturn 1 test flight which exceeded the test criteria. The Saturn 1 rockets were launched from here until 1968 when the complex became inactive.
In 2002 the complex was refurbished and repurposed for a new range of Boeing Delta IV rockets. The Delta IV and Atlas V (LC-41) now provide the main platforms described as Evolved Expendable Launch Vehicles for launching space ships into the upper atmosphere and beyond.
This site is now used to launch the latest GPS satellites on the Delta IV launch vehicle, as well as a number of spacecraft for the military and other agencies. Currently there are 3 variations of the Delta IV all having different booster configurations. These are the Delta IV, the Delta IV medium and the Delta IV heavy.
The best place to view launches from LC-37B is on the SR401 around the back of Port Canaveral 1/2 mile before the gates to the Cape Canaveral Air Force Base. From here there is a clear view of the rocket on the launch pad unobstructed by the umbilical tower at about 8 miles distance.