The Ryomyong Street development is a collection of residential tower blocks of various shapes - round, square and octagonal with the tallest proclaimed as 70 storeys, or 234 metres, high, and including nearly 5,000 apartments in total.
It stands just down a wide avenue from the Kumsusan Palace of the Sun, where the bodies of Kim's father and grandfather the North's founding father Kim Il-Sung lie in state, and its completion was repeatedly promised in time for Saturday's 105th anniversary of Kim Il-Sung's birth.
Tens of thousands of soldiers, officials and citizens packed a plaza from early morning, waiting in the cold Pyongyang spring air for hours before Kim made his entrance, leading a delegation of senior officials and generals onto the dais.
Addressing the throng, Prime Minister Pak Pong-Ju lauded Kim, the third of his family to rule the country.
"I would like to express the greatest thanks in the name of the people and the army to great leader comrade Kim Jong-Un, who wisely led this construction to victory," he said.
The project was a demonstration of "the 'do or die' spirit of our people and army who are willing to implement the Party's orders in all cases," he said, and "a victory against imperialists' sanctions."
There is speculation it might conduct a sixth nuclear test to coincide with the Kim Il-Sung anniversary. US President Donald Trump has dispatched an aircraft carrier group to the Korean peninsula in a show of force.
Such tensions were entirely absent as Kim took a pair of scissors proffered from a tray and cut a wide red ribbon to rhythmic cheers from the crowd. He waved to his admirers before turning and walking back to his Mercedes limousine.
North Korean authorities seek to present their isolated, impoverished country as prosperous and modern, and the project is the third of its kind in as many years in Pyongyang, but by far the largest at nearly 5,000 flats in total.
The showpiece penthouse apartments at the top of the tallest tower offer impressive views over the capital and the surrounding countryside, and are furnished with ice green wallpaper and purple sofas - but had no hot water.
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