Complex sentence: The bridge over the River Wye was completed in 1874, a few months after the lines official opening ceremony, on the bridges completion the line was extended to Monmouth Troy, the extension was officially opened on 1 May 1874.
Split into simpler sentences: The bridge over the River Wye was completed in 1874, a few months after the lines official opening ceremony. On the bridges completion the line was extended to Monmouth Troy, the extension was officially opened on 1 May 1874.