From the vertiginous belltower of Leuven’s university library, you get a great view across the mottled rooftops of Belgium’s most underrated city. Leuven isn’t swarming with sightseers, like Bruges. It isn’t choked with commuter traffic, like Brussels. It’s lively and compact, ideal for a weekend away – so why have most British travellers never even heard of it? Search me.