Bratislava slovakia Europe Prehistory (2800 – 450 BC)
The castle, like today's city, has been inhabited for thousands of years, because it is strategically located in the center of Europe at a passage between the Carpathians and the Alps, at a very important ford used to cross the Danube river, and at an important crossing of central European ancient (trade) routes running from the Balkans or the Adriatic Sea to the Rhine river or the Baltic Sea, the most important route being the Amber Route.

The people of the Boleráz culture (the oldest phase of the Baden culture) were the first known culture to have constructed settlements on the castle hill. This happened around 3500 BC (i.e. in the high Eneolithic Period). Their "castle" was a fortified settlement and a kind of acropolis for settlements in today's Old Town of Bratislava.

Further major findings from the castle hill are from the Hallstatt Period (Early Iron Age, 750 – 450 BC). At that time the people of the Kalenderberg Culture built a building plunged into the rock of the castle hill. Again, the "castle" served as an acropolis for settlements found in the western part of the Old Town.Castle in ruins (1811 – 1953)
The destroyed castle gradually went to the dogs. The military sold parts of the main castle buildings to people as material buildings in the surroundings. Between the two world wars the castle wanted to demolish to build government offices and university district on the castle hill and in its surroundings in the first Czechoslovak Republic and in the first Slovak Republic. Many parts of the site however continued to be used as barracks and adapted accordingly till 1946.

In 1946, the ruin was opened to the public. Two years later, the town constructed an amphitheater in the northern part of the castle site. The amphitheater was in use for some 15 years.
Bratislava Castle and the roofs of Old Town, as seen from eastFinally it was decided to restore the castle. Archaeological and architectonic research started in 1953 and long restoration works began in 1957. The restoration was done to the last (Baroque) state of the main building, but at many places older (Gothic, Renaissance) preserved elements or parts have been restored. The Theresianum has not been restored and the Hillebrandt building of 1762 was restored only around the year 2000. The Slovak painter Janko Alexy gained recognition for the restoration of the castle. The finishing of the restoration in 1968 was interrupted in August 1968, when the castle was occupied by Warsaw Pact troops (see Prague Spring). On 28 October 1968, however, the Federation Law, turning the centralist state of Czechoslovakia into a federation of a Czech Socialist Republic (later called Czech Republic) and a Slovak Socialist Republic (later called Slovak Republic), was signed in the so-called Federation Hall of the castle. On 3 September 1992, the new constitution of independent Slovakia was signed in the Knights Hall of the castle.

Since 1968, the castle has been housing expositions of the Slovak National Museum and at the same time its rooms have been used by the Slovak National Council (today the National Council of the Slovak Republic) for presentation purposes. In 1992, the castle housed a branch-office of the Czechoslovak president temporarily and later in the 1990s the Slovak president temporarily. It still houses the museum and the presentation rooms for the National Council of the Slovak Republic and for the president. A new restoration has been planned for years, because since 1968 (except for adding the Hillebrandt building) only minor adaptations have been performed, such as in 1988 creation of the Treasure Chamber, in 1995 replacement of glass in the arcades of the solemn staircase, and in 1996-97 a complete repair of the roof. The last minor adaptations occurred on the occasion of the Bush-Putin Bratislava summit in February 2005.

A massive reconstruction was started in 2008. It should take 5 years and cost 1.5 to 2 billion Slovak korunas (47.06 to 62.75 million euro).