Rome is home to dozens of beau­ti­ful build­ings wor­thy of a men­tion on this list, but the Pan­theon is prob­a­bly its best-look­ing. The ‘Tem­ple of the Gods’ was build around AD 126 but was destroyed at least twice, then rebuilt. Orig­i­nal­ly it had a rec­tan­gu­lar struc­ture, but it evolved into the beau­ti­ful dome we recog­nise and love today.