Czechoslovak "Benesh line"
Like other European countries during 1930's, also Czechoslovakia noticed growing threat of German dictatorship and started with construction of defence system along its borders. However, not only fortresses and bunkers were intended to prevent country from alien's attack. Huge amount of money was also spent in new guns and army. In fact, in 1938 even half of the state budget was planned for army modernisation and defence!
Aim of fortifications was originally to prevent country from crossing Moravian borders by enemy forces from the North and South, so they cannot cut country into two parts and Czechoslovak army is able to operate whole inland as one big force. As soon as in 1938 this plan changed, because Romania in South-East stayed the only allied neighbour. All others like Germany, Hungary and even Poland were considered enemy and government wished to defend all borders as much as possible. Fortifications were to be constructed almost all around the country then. It is sometimes named "Benesh line" abroad, though Czech would probably never use this. Czech people simply call it "border fortifications".
For construction of border fortifications, a new army department (so called ROP, which is Czech abbreviation for Direction of Fortifying Works) was established in Prague in 1934. It developed several programmes. Regarding the last approved one, construction should last until 1950's when all paths or roads (no matter how important or wide) would be blocked by heavy concrete casemates armoured by anti-tank guns or heavy machine guns, depending on terrain. When the construction was stopped due to sign of Munich Agreement in September, 1938, there were about ten thousand small pillboxes and almost tree hundred heavy casemates including artillery fortresses built, all around the country.
Heavy casemates were fully comparable to those at Maginot line in France. They even had more modern guns which had been developed in Skoda Plzen especially for use in fortifications. These comprised heavy machine gun model 37 and anti-tank gun model 36 (Germans adopted it later as PAK 36(t).). One of the unfinished artillery fortresses - Stachelberg, was planned to have similar firepower as French fortresses Hochwald or Hackenberg.
Starting in October 1938, Germans began to test bunkers abandoned by Czechoslovak army in surrended border areas. They tried to shoot them with various ammunition, damage them with explosives etc. Moreover, special forces were trained for capturing fortresses (one of them succeeded later at Belgian Eben Emael). During these tests, Germans recognized quality of works, especially of armour parts like domes, cupolas and embrassures. By the end of the Second World War, many of armoured parts were removed and used by Germans on their own fortifications.
After the Second World War, beginning in 1950's, Czechoslovak army considered fortifications at the South and Western border to be still useful against new enemy in the West. Heavy casemates built there were modernised. Main change was replacement old anti-tank guns Skoda model 36 by newer modernised Russian guns of calibre 85mm from T-34 tank. Regarding light fortifications, many of pillboxes were reinforced by adding earthy ramparts at the rear side so the pillboxes could better withstand an atomic blast. These fortifications were withdrawn from use in 1990's after fall of Communist regime.
Since 1990, many museums have been established, mainly on Northern border of Moravia. However, most of casemates stayed overgrown and abandoned until recently, as they had been badly damaged during WWII and soon after. Beginning in about 2000, Czechoslovak fortifications have become quite popular in the Czech republic and many groups have been formed in order to occupy themselves by reconstruction of those old concrete ruins. Unfortunatelly it means that many casemates are closed now. On the other hand, they are not so overgrown, so it is easier to take pictures.