Complex sentence: In 1898 Henrik Koestler met Adele, married her in 1900, and set up household in Budapest, where on 5 September 1905, Arthur, their only child, was born.
Split into simpler sentences: In 1898 Henrik Koestler met Adele, married her in 1900, and set up household in Budapest. On 5 September 1905, Arthur, their only child, was born.