Pompeii
The ruins of Pompeii have always been site to see on my bucket list. With so many ancient ruins destroyed or at least left in ruble, it was so amazing to witness a city that was almost literally frozen in time.
One of the most fascinating aspects of this city was the sheer size of it. I had always imagined Pompeii as being small, with a few houses left intact. Yet there were storefronts, marketplaces, baths, villas, theaters, and even infamous brothels still in place. This ancient civilization had advanced methods of urban design, water transport (although unfortunately involving lead pipes), acoustics, heating and cooling, etc. It was all truly remarkable.
After receiving a guided tour of most of the city, we ended with a view of Mt. Vesuvius (which we had actually climbed to the top of previously). The entire geography changed because of this volcano. The sea is much now farther away from the city compared to before it erupted, and the mountain itself is basically split in half forming two instead of one.
Although this disaster was a horrible tragedy for the people of Pompeii, it at least gave future generations a glimpse of the life in the past.