He is very familiar with Petrovaradin fortress (city of Novi Sad, Serbia); he has been exploring it since 1960. In 1965 he managed to decipher orientation marks at the crossroads and establish the logic of subterranean labyrinth with "^", "Y" and "T" crossroads. This approach helps him to examine the 20km deep undergrounds of the fortress in a faster and safer manner.
His engineering and ecological projects inspired by Petrovaradin fortress are in practice: "Selfheating ecological house", "Mushroom garden and greenhouse with reflecting surfaces" (mushroom gardens for growing bukovače near Čenej and Petrovaradin, Serbia, were built), Project "Forests for food production" (in use on several locations in the province of Vojvodina, Serbia and Montenegro) and "Autonomous battery charger".
In 1975, librarian Srećko Drk hired him as a guide for less known parts of the fortress especially subterranean military galleries.
Novi Sad museum awarded him with the letter of thanks for the "ardent contribution in research of the Petrovaradin fortress".
In the late 70's, as a member of scientific and technical editorial board of the Cultural Center in Novi Sad, he organized and lectured at panels about Petrovaradin fortress. Some of the participants were an academician and a professor Bogdan Brukner and a professor Milan Vranić.
An idea of a modern sod house as a new way of living gave him élan to continue with researching subterranean galleries.
In 1983, Veljko Milković and Mr. Srećko Drk founded "The club of friends of Petrovaradin fortress" within "Vladimir Nazor" library in Petrovaradin (Serbia).
In his numerous lectures and during short excursions he talked about dangers, but also about great tourist potential of Petrovaradin, Fruška Gora, Srem (Serbia) and the central part of the (river) Danube-basin.
During public appearances in previous years, Veljko Milković announced major archaeological discoveries from Palaeolithic age at the location of Petrovaradin fortress and in the central Danube basin. Experienced archaeologists stated that "it is beyond dreams" and that it was "absolutely unexpected"...
But it happened and it was confirmed by the latest archaeological discoveries from Palaeolithic age. In his numerous public appearances, Milković claimed that the central Danube basin is a cradle of prehistoric period, which was confirmed by the recent discoveries by European scientists. He is also in possession of a unique and unusual archaeological collection. He also gathered numerous minerals and fossils, from the Danube-basin, as well as remains of previous civilisations.
In his research study he worked hard on gravitation phenomenon and also on the improvement of anti-gravitational experiments and, connected to that, anti-gravitational operating systems.
Among other things in his experiments, he managed to get 12 times more output energy than input energy. In last 10 years, no one argumentatively disputed research and measurings carried out by Milković. Through such achievements, Veljko Milković laid the path for new challenges in physics in the 21st century, which could be the forerunner of the new great scientific revolution.
So far he has published the following books:
• "Solarne zemunice - dom budućnosti"
("Solar sod houses - the house of the future"), (1983),
• "Ekološke kuće"
("Ecological houses"), (1991 - printed in four unedited editions),
• "Šume za proizvodnju hrane - zamena za njive"
("Forests for food production"), (1992 - translated into Esperanto the same year),
• "Ka antigravitaciji - kompaktna vozila"
("Towards anti-gravitation compact vehicles"), (1994),
• "Antigravitacioni motor / Anti-gravity motor"
("Anti-gravity motor"), (1996 - with translation into English),
• "Perpetuum mobile"
("Perpetuum mobile"), (2001),
• "Petrovaradin kroz legendu i stvarnost"
("Petrovaradin through legend and reality"), (2001),
• "Petrovaradin i Srem - misterija prošlostit"
("Petrovaradin and Srem - mystery of the past"), (2003),
• "Svet misterija - novi pogledi"
("The world of mysteries new views"), (2004),
• "Petrovaradinska tvrđava - podzemlje i nadzemlje"
("Petrovaradin fortress over and underground"), (2005),
• "Novi turistički potencijali"
("New tourist potentials"), (2006) and
• "Petrovaradinska tvrđava - kosmički lavirint otrkića"
("Petrovaradin fortress - cosmic labyrinth of discoveries"), (2007).
("Solar sod houses - the house of the future"), (1983),
• "Ekološke kuće"
("Ecological houses"), (1991 - printed in four unedited editions),
• "Šume za proizvodnju hrane - zamena za njive"
("Forests for food production"), (1992 - translated into Esperanto the same year),
• "Ka antigravitaciji - kompaktna vozila"
("Towards anti-gravitation compact vehicles"), (1994),
• "Antigravitacioni motor / Anti-gravity motor"
("Anti-gravity motor"), (1996 - with translation into English),
• "Perpetuum mobile"
("Perpetuum mobile"), (2001),
• "Petrovaradin kroz legendu i stvarnost"
("Petrovaradin through legend and reality"), (2001),
• "Petrovaradin i Srem - misterija prošlostit"
("Petrovaradin and Srem - mystery of the past"), (2003),
• "Svet misterija - novi pogledi"
("The world of mysteries new views"), (2004),
• "Petrovaradinska tvrđava - podzemlje i nadzemlje"
("Petrovaradin fortress over and underground"), (2005),
• "Novi turistički potencijali"
("New tourist potentials"), (2006) and
• "Petrovaradinska tvrđava - kosmički lavirint otrkića"
("Petrovaradin fortress - cosmic labyrinth of discoveries"), (2007).
Milković also published noticeable feuilletons and notes:
• "Niskoenergetski život"
("Low-energy life"), (1996),
• "Energetski potencijal rečnog zaliva"
("Energetic potential of the river bay"), (1996),
• "Prethodna civilizacija"
("Previous civilisation"), (1999),
• "Misterije Petrovaradinske tvrđave"
("Mysteries of Petrovaradin fortress"), (1999),
• "Petrovaradinska tvrđava između legende i stvarnosti"
("Petrovaradin fortress between legend and reality"), (1999) and
• "Nestale civilizacije"
("Missing civilisations"), (2000).
("Low-energy life"), (1996),
• "Energetski potencijal rečnog zaliva"
("Energetic potential of the river bay"), (1996),
• "Prethodna civilizacija"
("Previous civilisation"), (1999),
• "Misterije Petrovaradinske tvrđave"
("Mysteries of Petrovaradin fortress"), (1999),
• "Petrovaradinska tvrđava između legende i stvarnosti"
("Petrovaradin fortress between legend and reality"), (1999) and
• "Nestale civilizacije"
("Missing civilisations"), (2000).
His book have been accepted both in domestic and foreign prestigious libraries, such as the Library of Congress, Washington DC and his publications can be found in the British Library in London, Moscow Library and Library of Alexandria. His publication have also been quoted in many Internet encyclopaedias and other sources.
He also found the solution how to lessen the problem of the "endangered inventor" and needs to make his secret public. That is exactly what Veljko Milković is doing by publishing his books and publications.