Acropolis

I have never taken a guided group tour, but here are 2 of those that are possible and reliable:

Athens Walking Tours

https://www.athenswalkingtours.gr/athens-tours/19-just-the-acropolis-tour.html

Or

Alternative Athens

https://www.alternativeathens.com/

Avoid websites like Get Your Guide, Viator or e-tickets which are only intermediaries just like booking is for accommodation

Whatever your choice, check that the tour is provided by a licensed guide who are the only ones authorized to accompany you to the archaeological sites. (some guided tour proposals make you think of a visit to the sites when you will only see them from the outside or from a car)

If you need to buy your tickets the official website is this one:

https://hhticket.gr/tap_b2c_new/english/tap.exe?PM=P1P&place=000000002

Note that you must specify the day and time to visit the Acropolis (time slot). Make sure to be at the entrance 30 minutes before your chosen time slot, entrance is available 15' before to 15' after the time of your choice.

Jo Lui, this is the most succinct yet accurate and informative answer to the Acropolis Question that i have eeen in a long time. To save effort and serve inquirers better, I'm bookmarking it, and will just offer it up in future. Many many thanks!!

Thanks for the suggestions. I appreciate it.