The observatory was officially inaugurated on June 29, 1985, by the Spanish royal family and six European heads of state. Four helicopter pads were built at the observatory to allow the dignitaries to arrive in comfort. The observatory has expanded considerably over time, with the 4.2m William Herschel Telescope opened in 1987, the Nordic Optical Telescope in 1988 and several smaller solar or specialized telescopes; the Galileo National Telescope opened in 1998 and the Gran Telescopio Canarias opened in 2006, with its full aperture in 2009.[citation needed]