Complex sentence: The area now comprising the city of Jūrmala has formerly been part of Riga, bearing the name Rīgas Jūrmala, but some parts of the city like Sloka and Ķemeri have been known as health resorts for centuries.
Split into simpler sentences: The area now comprising the city of Jūrmala was formerly part of Riga, known as Rīgas Jūrmala. Some parts of the area, like Sloka and Ķemeri, have been known as health resorts for centuries.