My work takes me frequently to Vienna. Only a few times I have half a day off there.
The short distance from Vienna to the border with Slovakia makes it sometimes possible to visit the border. In April 2014 I made the first short trip. First I took the slow train to Wolfsthal (75 minutes) and then I had to walk another hour before I reached the first border stone. After this complicated travel the remaining time was rather short, but it was worth it!
After this first trip I made more trips, taking a train or a rental car to the border area.
The border stones on the border between Slovakia and Austria, which in total is only 91 kilometers long, consist a number of series, ranges that are designated by the Roman numerals I to IV. The border stone range III (where my first trip started) begins east of Wolfsthal where the boundary leaves the Danube.
This range III ends a kilometer under Kittsee on the old road to Bratislava.
Range IV start there and ends at the tripoint Austria - Slovakia - Hungary.

When the boundary stones are placed is unknown to me. They are well maintained for sure. Slovakia has a checkered history, until 1918 to was a poart of Austria-Hungary. I assume that several boundary stones were reused.
There are basically three types of boundary stones can be distinguished:
- Little ones, protruding about 50 inches above the ground. These look fairly new;
- Bigger ones, these have a slightly larger size and stabbing about 80 cm above the ground.
Some large boundary stones are old: these are reused certainly. Sometimes the year '1835; can be read, sometimes there are also letters, such as 49 "EPP". Some seem to have contained weapons, but they are chiselled. In some cases, the new border stone is close to an old one, like III-12.
These ancient stones are lettered, but in most cases is't no longer possible to decipher what it says.
- Finally, there are tall, narrow border posts. I found a couple of these in a swampy area, a dry creek in summer.

The stones are placed in two ways:
1. directly on the border; which is also the most obvious place. These stones contain an "Ö" on the Austrian side and a "S" on the Slovakina side of it.
2. on both sides of the border, so one boundary stone in each country with the characteristics of this country on it: An "Ö" on the Austrian stone and a "S" on the Slovakina one. On the border itself there is a small unnumbered stone. In the case of this construction, there is a kind of strip between the two stones, looking like "no man's land". Such no man's land is used to raise a barrier between the two countries: a landgrave with or without thicket, a didge, a canal, a fence, a fence with barbed wires, a fence with high voltage wires, cameras, watchtowers with armed soldiers. All combinations are possible. Especially in countries with strict control or countries whit hostil regimes, such constructions are used. See for example the border Lithuania - Belarus which is heavily guarded since it's an EU external border. Czech-Slovakia belonged to the Eastern Bloc countries and used to have also a protected and guarded border until 1991. Now Slovakia is part of the EU the SK-AT border is an open border. On several places you will still find a ditch or a thicket. Other traces of that time, like fences are disappeared.

Range III, starting at the Danube
Range IV, starting near Kittsee
Tripoint AT-SK-HU