Complex sentence: It could accommodate up to 1,000 men but by the mid- 19th century the buildings were in a dire condition and in 1872 new barracks were completed in the suburb of Maryhill.
Split into simpler sentences: It could accommodate up to 1,000 men but, by the mid- 19th century, the buildings were in a dire conditiond. In 1872, new barracks were completed in the suburb of Maryhill.