What is the biggest plane in the world?

Here's some information about the biggest plane in the world, the Antonov An-225 Mriya:

The Antonov An-225 Mriya was a strategic airlift cargo aircraft designed by the Antonov Design Bureau in the Ukrainian SSR within the Soviet Union during the 1980s. It was the largest and heaviest airplane ever built, with a maximum takeoff weight of 640 tonnes (710 short tons).

Only one An-225 was ever completed. Its maiden flight was on December 21, 1988. It was powered by six turbofan engines and featured a unique design, including a twin-tail.

The Mriya's primary mission was to transport oversized and exceptionally heavy cargo, such as space shuttle orbiters. It notably carried the Buran spaceplane for the Soviet space program. After the collapse of the Soviet Union, the sole completed An-225 was refurbished and used for heavy cargo transport by Antonov Airlines.

Sadly, the An-225 Mriya was destroyed in February 2022 during the Russian invasion of Ukraine at Antonov Airport in Hostomel. There have been discussions about potentially rebuilding it, but the feasibility and timeline remain uncertain.