Complex sentence: Its construction was started in 1868 and finished in 1870; at the time it was among the most important stations in the country due to its size, the funds invested in it, and the amount of traffic.
Split into simpler sentences: Its construction was started in 1868 and finished in 1870. At the time it was among the most important stations in the country due to its size, the funds invested in it, and the amount of traffic.