It may only be November, but festivities are in full swing as Christmas markets have decorated high streets with wooden chalets, assorted wreaths, seasonal treats and the scent of spiced mulled wine. There's a catalogue of markets to visit across Europe for a wintery weekend getaway, and there's one that's just over four hours from the UK by train that is completely underground. In the charming Dutch town of Valkenburg, you can find Europe's largest underground Christmas market in the Municipal