Complex sentence: The London Brighton and South Coast Railway built a roundhouse a few yards north of the station on the lower level in 1869, extended with a second adjoining roundhouse in 1870 and a third in 1889.
Split into simpler sentences: The London Brighton and South Coast Railway built a roundhouse a few yards north of the station at the lower level in 1869. This was extended with a second adjoining roundhouse in 1870 and a third in 1889.