[[Imej:Bandar_Hitler_Germania.JPG|thumb|right|250px|Model pelan Hitler untuk Berlin]]
'''Welthauptstadt''' ("Ibu Negara Dunia") '''Germania''' adalah nama yang diberikan oleh [[Adolf Hitler]] kepada projek barunya untuk membaharukan ibu negara [[Jerman]], [[Berlin]] dan projek ini adalah sebahagian dari perancangannya untuk masa depan Jerman jika memenangi [[Perang Dunia Kedua]] . [[Albert Speer]], "arkitek pertama [[Third Reich]]" menghasilkan banyak pelan untuk membina semula bandar Berlin, namun hanya sedikit sahaja pelan itu dibina sebelum Perang Dunia Kedua.
Nama "Welthauptstadt" telah dipilih kerana pada masa itu senibina Berlin terlalu bersifat tradisional dan perancangan ini diperlukan untuk meletakkan Berlin setaraf dengan kualiti bandar dunia lain seperti [[London]], [[Paris]] dan [[Washington, D.C.]]
Some projects, such as the creation of a great city axis, which included broadening Charlottenburger Chaussee (today [[Straße des 17. Juni]]) and placing the [[Berlin victory column|Siegessäule]] in the center, far away from the [[Reichstag (building)|Reichstag]], where it originally stood, succeeded. Others, however, such as the creation of the [[Volkshalle|Große Halle]] (Great Dome), had to be shelved due to the beginning of war.
[[Image:1936 Olympics Stadium - Berlin.jpg|thumb|The Olympiastadion in 1993,mempunyai senibina pra-perang. Photo: [[:Commons:User:JGHowes|James G. Howes]].]]<!--attribution required: see image description page at http://en.wikipedia.org/wiki/image:1936 Olympics Stadium - Berlin.jpg-->
Langkah pertama untuk pelan ini adalah pembinaan [[Stadium Olimpik Berlin]] untuk [[Olimpik musim panas 1936]]. Stadium ini akan memperlambangkan kebangkitan kerajaan Nazi, Speer juga mereka
a new [[Reich Chancellery|Chancellery]], which included a vast hall designed to be twice as long as the [[Palace of Versailles#The Hall of Mirrors|Hall of Mirrors]] in the [[Palace of Versailles]]. Hitler wanted him to build a third, even larger Chancellery, although it was never begun. The second Chancellery was destroyed by the [[Red Army|Soviet army]] in [].
Almost none of the other buildings planned for Berlin were ever built. Berlin was to be reorganized along a central three-mile long avenue running through the [[Tiergarten]]. This would have served as a parade ground, and have been closed off to traffic. Vehicles would have instead been diverted into an underground highway running directly underneath the parade route; sections of this highway's tunnel structure were built, and still exist today. At the north end of the avenue, Speer planned to build an enormous [[dome|domed]] building, the [[Volkshalle]] (''people's hall''), would still remain the largest enclosed space in the world. Although war came before the building could be built, all the necessary land was acquired, and the engineering plans were worked out. The building would have been over two hundred meters (700 feet) high and two hundred and fifty meters (800 feet) in diameter, sixteen times larger than the dome of [[St. Peter's Basilica|St. Peter's]]. At the southern end of the avenue would be an [[arch]] based on the [[Arc de Triomphe]] in [[Paris]], but again, much larger; it would be almost a hundred meters (330 feet) high, and the Arc de Triomphe would have been able to fit inside its opening. The outbreak of [[World War II]] in [] caused the decision to postpone construction until after the war to save strategic materials.<ref>Speer, Albert (1970). Inside the Third Reich. Simon & Schuster. ISBN 0-684-82949-5.</ref>
Doubts persisted at the time as to whether the marshy Berlin ground could have taken the load of the proposed projects, leading to the construction of an ''exploration building'' (''[[Schwerbelastungskörper]]'', literal translation: Heavy load-bearing body), which still exists. It is basically an extremely heavy block of concrete used by the architects to test how much weight the ground was able to carry. Instruments monitored how far the block sank into the ground. The Schwerbelastungskörper sank 7 inches in the three years it was to be used for testing, a maximum depth of 2.5 inches was allowed. Using the evidence gathered by these gargantuan devices, it is unlikely the soil could have supported such structures without further preparation. <ref>History Channel, Cities Of The Underworld: Episode: 01 - Hitler's Underground Lair (5/5/07)</ref>
Disebabkan kita tidak mempunyai rujukan perkataan "Welthauptstadt Germania" selain dari autobiografi [[Albert Speer]], nama itu masih menjadi tanda tanya sama ada nama itu direka oleh Hitler atau Speer sendiri.
At the time of the initial invasion of [[Russia]] ([[Operation Barbarossa]]) in June 1941, Hitler expected to win victory in [[World War II]] by 1945, and he then planned, after completing the construction of the Welthauptstadt Germania [[City planning|plan]], to hold a great [[World's Fair]] in Berlin in 1950 and then retire to his hometown of [[Linz]]<ref> Speer, Albert ''Inside the Third Reich'' New York:1970--Macmillan P.139 </ref>.
In his 1992 [[Robert Harris]], author of the alternative history novel [[Fatherland (novel)|Fatherland]], speculates that Hitler's and Speer's vision of rebuilt and monumental Berlin would have been realized by []. Other researchers into the logistics of Hitler's Welthaupstadt have claimed that, owing to both the sheer amount of marble required and Berlin's marshy foundations, Germania would have sunk into the ground within a few years.