There’s a bunker, a hidden chess club, a haunting forest and a forgotten city-centre zoo, among a few other secrets held by the gatekeeper of Retiro Park. But dive in with the darkest, most disturbing secret of all: the ‘human zoo’…

An entire village was built to exhibit these unfamiliar people in their ‘natural habitat’, with thousands of curious spectators paying for a glimpse into their exotic world. Welcome to the darkest corner of Retiro Park: Madrid’s erstwhile ‘human zoo’.

Under a blanket of snow, I imagine Madrid to be as silent as the night. Not even a gust of wind could echo through the streets, never mind the infamous Madrileño hum. For those of us who arrived in Madrid in the last decade, the time-travelling journey that we’re about to embark on feels a little make-believe, but trust me – this really happened.