Successfully booked 5 tickets of official underground colosseum tour (in Italian)

My experience to share:
Experience to share:
1. Do get on the website beforehand and try few times to get familiar with where and how to book tickets
https://ticketing.colosseo.it/en/
2. Timing is important. DON'T give up when you cannot get tickets by the release time. Tickets are released throughout the hours, getting up at 2:30am EST is not a must. For example, 12:00PM tickets are released 6AM EST. I live in New York and got up at 5:50AM. By 6AM when i refreshed the website, all tickets for the underground (non-tour) are GONE for slots on or before 12pm. Attic Tickets were gone too... I was frustrated. I switched to underground tour tickets just to see. At first, only 1 ticket is available. Surprisingly, around 6:10AM Underground tour tickets in Italian are available for 4. Since the tickets can be held in cart for only 15 mins, some people probably didn't want the tickets in the end and dropped them from their cart. After created an account and bought 4 tickets, I still need one more ticket. I was thinking to book the last ticket as Arena only ticket. When I saw there were plenty of Arena tickets left for the time slot 12pm since there is no warning "Available (number of ticket left)." I decided to try the guided tour again and luckily I see one available and booked the last one.
3. This is a trick. Don't need to select the number of tickets on the top and just leave the number of tickets needed as 1 so you could see all available tickets. If I selected 5 tickets, the website would tell me unavailable since only 4 tickets left and i couldn't have booked the first 4 tickets. So you can leave the ticket number at top as 1 and add the number you need based on the availability when you add tickets to cart. This also saved a lot of time.
4. Do remember if you change the category, tickets in cart from other category get cleared out. For example, I added one area only ticket to my cart and then I got warning when I switched to tour ticket and try to add one tour ticket.
5. The tickets I got are in Italian but I will download a translation app on phone to translate from Italian to English.
Good luck!