We took the Metro to the Montmarte station and proceeded to go up to see the Sacre Coeur Basilica.  The Sacred Heart Basilica is amazing & the website needs to be seen:  <https://www.stspeterandpaulbasilica.com/what-makes-a-basilica>. Once done we walked down Pigalle  (the once famous street of riskay shops, prostitution, and bars).  It is way less dramatic than when I was here 50 years ago.  We ended the walk at the Paris Opera made famous in the Phantom of the Opera.