There is a new official website and booking platform for purchasing tickets to archaeological sites and museums:
The old website, hhtickets.gr, is still online, but it will redirect you to the new platform when you go to book a ticket.
Online tickets are currently available for admission through August 31.
This is good news, thanks for posting. Thought we'd have to wait until a week before leaving to get tickets but now much improved.
Note that there is now an option if you have already purchased your tickets and want to change the date and time slot selected. (You don't need to register on the website or have an account ID.)
You will just need your reservation ID (15 digits) and security code (8 digits) that were sent to you with your ticket.
Scroll down to the bottom of the homepage and click on Manage Ticket. From there, you can enter your reservation ID and security code to retrieve your ticket, and then change its date and time slot.
By clicking on the down arrow to the right of your ticket, you can also add it to your Apple or Google Wallet or download it as a PDF.
