I travelled on a Mercedes bus from Kabul through Kandahar to Herat. The trip was supposed to take about 12 hours. It took more like 18... with just one driver!
Herat was hot and extremely dry. I spent four nights there waiting for my Iranian entry visa. From there I took a local bus to the Mashad Campsite in Mashad, Iran. The big sight in Mashad was the blue tiled dome of the tomb of the Iman Riza.

In 1975 described the campsite as "75¢ per night, nice beds in concrete floored tents, lots of trees, lawns, tourists and a nice swimming pool."
In that time there were several companies doing overland bus tours from England out to India. One nearly empty bus -- the "Budget Bus" more suited for day trips to Brighton -- stopped and offered to take passengers back to Europe. I negotiated a ten day trip to Thesaloniki, Greece for $35 US!! We slept on or beside the bus and stopped two nights in both Tehran and Istanbul.

From Tehran the road went through the mountains. The last town before the Turkish border was in an extremely narrow valley. Just across the border was a view of Mount Ararat.
Along the way we stopped for a dip in a river beside the busy highway. (The dog was named Juanita and had travelled all the way from Columbia with its owner!)

We spent two more nights in Istanbul. I visited the Blue Mosque and the great Hagia Sophia. I also show a view of the floating bridge across the Golden Horn.