Honestly, nothing prepared me for just how big the Roman Colosseum is. They guess it held about 40k people but walking through it was like walking through a small modern baseball stadium, except it was built over 1,000 years ago.
@shabbir there’s a smaller 25000-seat one in Pula, Croatia that is in the best condition of the 6 remaining arenas, and if you go off season it’s often easy to be the only person there, as I was in Nov 2015. Amazing experience.