Pion HBT radii at $k_T$ = 0.3 GeV/$c$ for the 5% most central Pb-Pb at $\sqrt{s_{\rm NN}}=2.76 $TeV(red filled dot) and the radii obtained for central gold and lead collisions at lower energies at the AGS [35], SPS [36,37,38] and RHIC [39,40,41,42,30,43]. Model predictions are shown as lines.