You need to see this and it's on every Turkmenistan itinerary, however, I find the places near Mary nowhere near as good as Gonur which is further north through the desert. I was very disappointed with Merv before that spot. Then I noticed there are a few dozen spots as locations for the UNESCO property and the locals say UNESCO are stupid. Well basically the sites don't connect and weren't at the same time so you are combing them because of location only.

Gonur is a marvel though. It has hardly been excavated and will take a few more excavators to give their life like Victor did here. He spent over 40 years just exploring and digging, getting Turkmenistan citizenship in the meantime and being honest about it taking forever. "Don't excavate this building, I want to see the whole site first". Nowadays you can see the palace and surroundings but all houses outside of that are buried and you are basically stepping on them constantly. You will also step on pottery but it is apparently low quality stuff.

A trip to Gonur is usually only longet tours. It takes 2 hours from Mary just to reach it. There is also no road so it's desert sand roads almost all the way.

In off-season I was able to chat with the local staff a bit as they are still excavating in Spring and Autumn. They only speak Turkmen and Russia but the guide would help a lot. There is power and shade near the site which would otherwise be a tough place. It was 42°C on that day. There are two other buildings that show the buried horse (as seen in the National Museum as a photograph) and a replica of the chariot which must be in another museum. All local skeletons are now just for show but you'll be happy it's inside a building.

You can easily spend hours exploring here but as it was hot the hour was enough to see the palace, burners and overall look of the city. Once the water ran out they all left.

Would highly recommend Gonur but the parts in the south not so much.