An <a href="https://en.wikipedia.org/wiki/2017_Catalan_independence_referendum" id="mwAdE" rel="mw:WikiLink" title="2017 Catalan independence referendum">independence referendum</a>, later declared illegal by the Constitutional Court of <a href="https://en.wikipedia.org/wiki/Spain" id="mwAdI" rel="mw:WikiLink" title="Spain">Spain</a>, takes place in <a href="https://en.wikipedia.org/wiki/Catalonia" id="mwAdM" rel="mw:WikiLink" title="Catalonia">Catalonia</a>.