How old is the biggest horse in world?

It's impossible to say for sure what the *oldest* biggest horse in the world is because:

* Horses have a finite lifespan: The average lifespan for a horse is 25-30 years, though some can live longer.

* We don't have records of all horses: There's no central registry tracking the age of every horse on the planet.

* "Biggest" is subjective: Do you mean the tallest, the heaviest, or some other measurement?

Instead of trying to find the *oldest* biggest horse, we can look at the *biggest* horses currently living:

* The tallest horse breed: The Shire horse holds the record for the tallest horse breed.

* The tallest horse ever recorded: "Big Jake" was a Shire horse that held the Guinness World Record for tallest horse at 6 feet 10.75 inches tall. Sadly, he passed away in 2010.

If you want to learn more about the tallest horse breeds or the record-holding horses, I recommend checking out resources like the Guinness World Records website or reputable horse breed organizations.