An enormous half-cylindrical shelter has been installed over the exploded reactor at the Chernobyl nuclear plant.
The structure, said to be one of the world's most ambitious engineering projects, is designed to prevent radiation leaks from the site of the world's worst nuclear accident.
The arch-shaped shelter reached its destination on Tuesday after two weeks of being moved towards the site on a system of hydraulic jacks.
The shelter now encloses the 'sarcophagus' that was hastily built by Soviet authorities in the immediate wake of the explosion 30 years ago.
The head of the Chernobyl shelter fund said the completion of the structure over the exploded reactor was like "closing a nuclear wound".
Hans Blix, a former United Nations weapons inspector, spoke on Tuesday (local time) at a press conference marking the completion of the project.
Ukranian President Petro Poroshenko said the new structure would ensure nuclear safety for a further 100 years.
The shelter, 275 metres wide and 108 metres tall, cost €1.5 billion (NZ$2.24 billion).
AP / Newshub.