derby was settled by romans – who established the town of derventio – saxons and vikings, who made derby one of the five boroughs of the danelaw. initially a market town, derby grew rapidly in the industrial era. home to lombe's mill, an early british factory, derby has a claim to be one of the birthplaces of the industrial revolution. it contains the southern part of the derwent valley mills world heritage site. with the arrival of the railways in the 19th century, derby became a centre of the british rail industry.