Complex sentence: The spa town of Buxton was developed by the Dukes of Devonshire as a genteel health resort in the 18th century; now the largest town in the Peak District, it has an opera house with a theatre, museum and art gallery.
Split into simpler sentences: The spa town of Buxton was developed by the Dukes of Devonshire as a genteel health resort in the 18th century. It has an opera house with a theatre, museum and art gallery.