This Basilica was about a 5 minute walk from my hotel. I planned to just stop by for a few minutes to see it. Ended up spending more than an hour there and it was one of the highlights of my trip. The interior is overwhelmingly beautiful, second only to St. Peter's Basilica. I tried to take photos but everything is so ornate that it is impossible to capture! I found a 360 degree view online which I have been sharing with friends and family so that they can get a sense of the beauty and wonder of the place: http://www.vatican.va/various/basiliche/sm_maggiore/vr_tour/index-en.html
Definitely set aside at least an hour to see this, and if you have a chance check out the attached museum which can be accessed by passing through the gift shop. Tons of gold, papal robes, and other lovely items.
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