Complex sentence: In 1882 the Met extended its line from Aldgate to a temporary station at Tower Hill, the District completed its line to Whitechapel and on 6 October 1884 the temporary station was replaced with a joint station and the inner circle was complete.
Split into simpler sentences: In 1882 the Metropolitan extended its line from Aldgate to a temporary station at Tower Hill and the District completed its line to Whitechapel. On 6 October 1884 the temporary station was replaced with a joint station and the inner circle was complete.