The <a href="https://en.wikipedia.org/wiki/Treaty_of_Accession_2003" id="mwASU" rel="mw:WikiLink" title="Treaty of Accession 2003">Treaty of Accession</a> is signed in <a href="https://en.wikipedia.org/wiki/Athens" id="mwASY" rel="mw:WikiLink" title="Athens">Athens</a> admitting ten new member states to the <a href="https://en.wikipedia.org/wiki/European_Union" id="mwASc" rel="mw:WikiLink" title="European Union">European Union</a>.