and Liverpool Canal, which is the longest canal in England. Mainland Europe (the Netherlands and Belgium) can be reached from Hull via regular ferry services from P&O Ferries. Yorkshire also has air transport services from Leeds Bradford Airport. This airport has experienced significant and rapid growth in both terminal size and passenger facilities since 1996, when improvements began, until the present day. From 2005 until 2022, South Yorkshire was served by Doncaster Sheffield Airport in Finningley. Sheffield City Airport opened in 1997 after years of Sheffield having no airport, due to a council decision in the 1960s not to develop one because of the city's good rail links with London and the development of airports in other nearby areas. The newly opened airport never managed to compete with larger airports such as Leeds Bradford Airport and East Midlands Airport and attracted only a few scheduled flights, while the runway was too short to support low cost carriers. The opening of Doncaster Sheffield Airport effectively made the airport redundant and it officially closed in April 2008. The Doncaster Sheffield Airport has since closed and left South Yorkshire without an airport. Public transport statistics The average amount of time people spend on public transport in Yorkshire on a weekday is 77 minutes. 26.6% of public transport users travel for more than two hours every day. The average amount of time people wait at a stop or station for public transport is 16 minutes, while 24.9% of passengers wait for over 20 minutes on average every day. The average distance people usually ride in a single trip with public transport is 7 km, while 10% travel for over 12 km in a single direction. Architecture Fortifications Throughout Yorkshire many castles were built during the Norman-Breton period, particularly after the Harrying of the North. These included Bowes Castle, Pickering Castle, Richmond Castle, Skipton Castle, York Castle and others. Later medieval castles at Helmsley, Middleham and Scarborough were built as a means of defence against the invading Scots. Middleham is notable because Richard III of England spent his childhood there. The remains of these castles, some being English Heritage sites, are popular tourist destinations. Stately There are stately homes in Yorkshire that carry the name "castle" in a similar way to the non-distinctive use of chateau in French. The most notable examples are Allerton Castle and Castle Howard, both linked to the Howard family. Castle