St Paul's Cathedral, constructed at the turn of the 17-18C by Lorenzo Gafa, vies with the Co-Cathedral in Valletta in terms of sheer splendour. With its iconic dome and impressive facade, it is the must-see sight of Mdina, which it dominates. Be sure to admire the frescoes by Mattia Preti adorning the interior and the polychrome tomb stones. The nearby museum, which showcases many religious and non-religious artefacts, is also worth a visit.