I spent last weekend in Kazbegi.
I'll show you beautiful way to get from Tbilisi to Kazbegi.
You cant skip Ananuri Castle on your way to Kazbegi. Its only 70 km from Tbilisi. This Castle was used for military purposes.
Near the village Pasanauri you can see how two rivers Black and White Aragvi turning into Aragvi.
Afer Aragvi you will see "Panorama Gudauri", its also know as "Gudauri Friendship Monument". Its 120 km from Tbilisi. Panorama is decorated with Soviet style, with mosaics.
Gveleti Waterfall is located in Stephantsminda (village Gveleti), in English "Snake's Waterfall".
Mkinvartsveri is situated on the border of Kazbegi municipality. its 5047 meters in the sea level.
Some Photos with my Google Pixel