London's Big Ben is probably the world's most famous clock and central to the UK's New Year celebrations. But, in a digital world, what does it take to keep the analog 165-year mechanical clock on time? CNN's Isa Soares climbs the narrow stairs and goes behind the scenes of the iconic landmark to see what it takes to make sure London's New Year happens when it should. | CNN International

Big Ben bongs again - London's beloved bell resumes regular ringing after renovations