The airport opened on 25 October 1985 with three Aer Lingus charter flights to Rome: the official opening was on 30 May 1986. The site, on a hill in boggy terrain, was thought by many to be unrealistic, but the airport was built following a long and controversial campaign by Monsignor James Horan, the story of which has even inspired a musical. The primary motivation for building it was to attract pilgrims to Knock Shrine. Despite criticisms that the site was too boggy and too foggy, Horan delivered an airport within five years, primarily financed by a Government grant of £9.8 million. He died shortly after the opening of the airport, and his funeral was held at the then-named Horan International Airport. In recent times, Horan has been celebrated with a bronze statue erected at the airport. By 1988, over 100,000 passengers had passed through. Aer Lingus commenced flights from the airport to Birmingham in 1995. Since 2003, flag-carrier, low-cost and regional airlines including Aer Lingus, MyTravelLite, Bmibaby, Ryanair, Aer Arann, flybe, Lufthansa and EasyJet have added routes to Great Britain and mainland Europe. Not all have proven successful, but by 2005 the airport was handling 500,000 passengers per annum. It was voted Ireland's best regional airport in 2006 and 2009 by the Chambers of Commerce of Ireland. 2007 was a notable year, with scheduled transatlantic services to New York and Boston commencing in May, operated by the now-defunct Flyglobespan. A record 629,000 passengers used the airport in 2008, a 13% rise compared to the previous year. The installation of the Category II Instrument Landing System in April 2009 has resulted in a significant reduction in the number of flight diversions to other airports due to poor visibility – the airport is 200 metres above sea level. August 2009 was the busiest month for three years, with 81,000 passengers: 28 August was the busiest day in the airport's history, with over 4,500 passengers. In 2011, the month of August was the busiest in the airport's history with 84,052 passengers. 2011 was the most successful year to date with 654,553 passengers. The year saw the commencement of routes to Lanzarote, Tenerife and Gran Canaria operated by Ryanair and to Edinburgh operated by flybe. During September 2011 Ryanair celebrated its four-millionth passenger through the airport, while Lufthansa announced it would be commencing weekly flights to Düsseldorf in May 2012. In November 2011, Ryanair announced flights to Beauvais-Tillé, Frankfurt-Hahn, Bergamo-Orio al Serio and Girona-Costa Brava from March 2012. In January 2012 the 20th scheduled route was announced—flybe to Leeds, its third from the airport, from March 2012. Budget carrier BmiBaby announced in May 2012 that it was to axe its only route to Birmingham from 10 June, owing to the airline's takeover by IAG. Flights to Beauvais-Tillé and Frankfurt-Hahn have since ended. In 2013, Ryanair launched a weekly summer route to Málaga on Thursdays. Aer Lingus Regional, which took over the Birmingham route operating a daily service using ATR 72s ended service on 26 October. Flybe began four-times-weekly flights on the route on 27 October. On 31 October 2013, in response to the scrapping of the Irish travel tax, Ryanair unveiled three new routes from Knock to Glasgow-Prestwick, Kaunas and Eindhoven. However, these routes had all been withdrawn by the fourth quarter of 2014. It was announced in November 2017 that €15 million would be invested in improving and upgrading the airport in 2018 and 2019, to coincide with strong passenger growth. These plans include upgrading of car parks, passenger facilities, the terminal and resurfacing of the runway.