Ilkley is a spa town and civil parish in West Yorkshire, in Northern England. Historically part of the West Riding of Yorkshire, Ilkley civil parish includes the adjacent village of Ben Rhydding and is a ward within the metropolitan borough of Bradford. Approximately north of Bradford and 17 miles (27 km) northwest of Leeds, the town lies mainly on the south bank of the River Wharfe in Wharfedale, one of the Yorkshire Dales.
Ilkley's spa town heritage and surrounding countryside make tourism an important local industry. The town centre is characterised by Victorian architecture, wide streets and floral displays. Ilkley Moor, to the south of the town, is the subject of a folk song, often described as the unofficial anthem of Yorkshire, "On Ilkla Moor Baht 'at". The song's words are written in Yorkshire dialect, its title translated as "On Ilkley Moor without a hat."
The earliest evidence of habitation in the Ilkley area is flint arrowheads or microliths, dating to the Mesolithic period, from about 11,000 BC onwards. The area around Ilkley has been continuously settled since at least the early Bronze Age, around 1800 BC; more than 250 cup and ring marks, and a curved swastika carving dating to the period have been found on rock outcrops, and archaeological remains of dwellings are found on Ilkley Moor. A druidical stone circle, the Twelve Apostles Stone Circle, was constructed 2,000 years ago. Serious interest in the rock art of Ilkley began after the publication in 1879, by Romilly Allen, of "The Prehistoric Rock Sculptures of Ilkley" in The Journal of the British Archaeological Association.
The remains of a Roman fort exist on a site near the town centre. A number of authorities believe that the fort is Olicana, dating to 79 AD, but the identification is not settled. A number of Roman altars have been discovered dating to the reigns of Antoninus Pius (138 to 161), and Septimius Severus and his son Caracalla (211 to 217).
Three Anglo-Saxon crosses formerly in the churchyard of All Saints', but now inside the church to prevent erosion, date to the 8th century. The site of the church as a centre for Christian worship extends to 627 AD, and the present mainly Victorian-era church incorporated medieval elements.
The Domesday Book, of 1086, records Ilkley (Ilecliue/Illecliue/Illiclei/Illicleia) as being in the possession of William de Percy 1st Baron Percy. The land was acquired by the Middelton family of Myddelton Lodge, from about a century after the time of William the Conqueror. The family lost possession through a series of land sales and mortgage repossessions over a period of about a hundred years from the early 19th century. The agents of William Middelton (1815–1885) were responsible for the design of the new town of Ilkley to replace the village which had stood there before.
In the 17th and 18th centuries the town gained a reputation for the efficacy of its water. In the 19th century it became established as a fashionable spa town, with the construction of Ben Rhydding Hydro, a hydropathic establishment at Wheatley, a mile to the east, between 1843 and 1844. Charles Darwin underwent hydropathic treatment at Wells House when his book On the Origin of Species was published on 24 November 1859, whilst staying with his family at North View House (now Hillside Court). Tourists flocked to 'take the waters' and bathe in the cold-water spring. Wheatley was renamed Ben Rhydding after the Hydro, which has been demolished.
Other Victorian visitors to the town include Madame Tussaud. Today, the only remaining hydro building is the white cottage known as White Wells House. The cottage can be seen and visited on the edge of the moor overlooking the town.