The Michelin Green Guide to Rome lists thousands of objects to see, perhaps 8000 like the NGC. Similarly for Fodor's Guide. I see people checking off these objects (paintings, sculptures, fountains, streets, etc.) in their guidebooks, one by one, until they have seen all 8000. As for me, I sit in the Piazza Navona, perhaps the greatest urban square in the world, and sip expresso. These object-oriented people count the cracks in the cobblestones, probably, while I drink in, so to speak, the Bernini Fountains and watch the artists and listen to the street musicians.
Sometimes I sip expresso in the Piazza del Pantheon, opposite the oldest building still in use in the world. Recently, using a guidebook, I found a little church a block away that had an elephant sculpture on a pedestal, probably two thousand years old, in front of it. In the church were some statues. I paid attention to the one by Michelangelo, of Christ carrying the cross, which has some of the feel of his David, in Florence.
Sometimes I go to the Spanish Steps, possibly the most beautiful set of stairs in the world. Or I walk through the Piazza del Campidoglio, perfectly proportioned, designed by Michelangelo. Or I go to the Trevi Fountains and listen to the young Italian people sing and play the guitar in the moonlight.
Although I see some new things every time I go to Rome, I will never see or try to see the 8000 things in the Guidebook, nor even the Michelin 400 I or the Michelin 400 II, if there are such things. And I will never place checkmarks in my guidebook to indicate objects found and conquered. I may eventually and unintentionally see 800 "objects" or "sights" in Rome, depending on how you count, in fact I may have already, but I won't know it and I won't be counting and I won't be using anyone else's list and I won't be working toward a certificate.
But I will be having yet another expresso in the Piazza Navona, the Piazza del Pantheon, and similar places, and drinking in the atmosphere and the feeling of Rome and its people.
Just my way of doing things.