Athens and Islands for Mobility Impaired

Take a bus day tour. The stairs , cobbles broken pavement will be a challenge.

Ok thanks. I will check that out!

How far can he walk with the assistance of a walker? Test him on perfect flat territory, then on cobblestone, broken pavement, with some ups and downs etc. If it is a walker with a seat then test his capabilities with resting as needed. Measure his actual capabilities, not the hopeful ones.
Depending on the severity of his Parkinson's, and especially if stress or physical exhaustion aggravates symptoms, you might wish to consider a collapsible wheelchair. And remember that the "healthy" people will also become fatigued.
You need to experiment with all of this a long time before you go. A similar idea applies to luggage. Pack everything you think you need, then walk a thousand feet; if you are still frisky, then fine; if not, start dumping and/or planning on lots of uber/taxis.
I also recommend a medical summary in clear, simple English. Plus a list of prescription drugs that have their chemical name plus proprietary name[s], plus, if possible, which company produces them. And then take smart phone photos of them and other important documents and email them to yourself, your friends and family back in the US.

Take two separate containers, each of which has enough drugs for the entire trip and place each container in different luggage, just in case of loss or theft of one piece of luggage.
Have a wonderful trip, and I commend all of you for undertaking this trip.
Harvey

Thank you for all your very helpful ideas and input. This is very good advice. He is able to walk about 30 minutes but that's with the best of circumstances for sure. We will hire a car to drive us everywhere the first day so he is able to see the main sites and then it will be cabs or cafes for he and his wife and to meander as much as they are able. We are aware that our trips will now involve cabs and ubers. He says he is ok with us leaving him at a cafe where he can read and people watch, that it is better to be there than not to be. We are hoping it will all work but we are going to take you advice.

There is an elevator at the Acropolis for the handicapped to use.

This website discusses people who use a wheelchair but it may also apply in your situation:

https://www.sagetraveling.com/Athens-Wheelchair-Accessible-Travel-Tips

The Acropolis elevator is only available by appointment and you won't be allowed to accompany him on it.

According to Matt's Athens Guide: a person who is disabled can be accompanied by another person who is assisting them.

https://www.athensguide.com/acropolis.html

Scroll down to near the bottom of the page.

The Acropolis Elevator

For those who have difficulty with steps or are in wheelchairs there is an elevator on the northwest side of the Acropolis. If you ask when you get your tickets at the ticket booth they will point the way to you. If you are coming with a taxi and have mobility issues ask the driver to get your tickets and take you the rest of the way to the elevator. You should call the day of your visit to make sure that the lifts are working. (0030) 210 3214172 or (0030) 210 3214173. Get there as early as possible to avoid lines. Please keep in mind that this elevator is strictly available to disabled visitors and people assisting them only. That means you can't use it just because you don't feel like climbing the steps.

Matt Barrett's Guide is comprehensive but not always updated ... and I have so often heard of disappointments re the Acropolis elevator, if one only inquiries on the day. It is wise to try to contact several days in advance, and then the day before, and again the day of. Sometimes people have made what they thought were firm arrangements, then found that the person to run the elevator was not available. Check, then re-check, then check again (also confirm that a helper can be with the disabled person).

According to the Greek Ministry of Culture the elevator has been repaired and is up and running. Whether it will be operating when you go is another question.

Matt's Guides are excellent but as stated not always updated. Use it more as a "guide" than rely on it for the gospel truth.

However, check out this website for more info:

http://barrierfreetravels.com/2019/06/acropolis-elevator-up-and-running/

Thank you Tommy and Janet for your invaluable information. We will call before, and several times, to check on the elevator. We are doing this visit with a private car so if the worst happens and our friend cannot get up to the top, he will have a comfortable car to wait in. Hopefully that won't happen. Thank you for all this information. It is is most appreciated!