We don't know much about what goes on inside Yarl's Wood. It's a detention centre in Bedfordshire – the most notorious of its kind in the UK – where asylum seekers and "immigration offenders" can be held indefinitely while waiting to find out if they're going to be deported.
Over the years, Yarl's Wood has found itself at the centre of some controversy, leading to staff being fired or dismissed based on information uncovered in investigations by The Observer newspaper in 2013 and Channel 4 in 2015.
Yesterday, thousands of protesters hopped off coaches and gathered outside Yarl's Wood to call for the centre's closing. People let off colourful flares, chanted and banged their feet and hands against the high chainlink fence that rings the centre, while some women held inside waved their hands and makeshift flags outside their windows to acknowledge the protest. We were there, amongst the coachloads of protesters from around the country, to see what all the fuss was about.