Karnataka

It took around 20 years to build the largest Egyptian pyramid, (the Great Pyramid of Giza)
From wikipedia:

The Great Pyramid of Giza (also called the Pyramid of King Khufu' and Pyramid of Cheops) is the oldest and largest of the three pyramids in the Giza Necropolis bordering what is now El Giza, Egypt, and is the only one of the Seven Wonders of the Ancient World that survives substantially intact. It is believed the pyramid was built as a tomb for Fourth dynasty Egyptian Pharoah Khufu (Cheops in Greek) and constructed over a 20 year period concluding around 2540 BC.

It is believed the pyramid was built as a tomb for Fourth dynasty Egyptian pharaoh Khufu and constructed over a 14 to 20 year period concluding around 2540 BC
The Khufu's Great Pyramid was constructed in 2560 BCE and it took 20 years to deliver. It was the tallest man made construction until the Pharos of Alexandria was build at 280 BCE.
20 years
It took a period of 14-20 years to build the Pyramid of Khufu. ----

it took more than a day and less then 21 years. he used 10,000 slaves and free men.

10,000 to 20,000 naked slaves toiled in the blazing Egyptian sun for 14 to 20 years to build this symbol of vanity for a single man Pharaoh Khufu.
The Pyramid of Khufu also known as The Pyramid of Cheops [his Greek name] or The Great Pyramid of Giza was built for the fourth dynasty pharaoh Khufu over a period of about 14-20 years as his tomb around 2550 B.C.

See the link below.
The answer is: between 14 and twenty years 14 to 20 years
It took 20 years. Over that period 20,000 naked slaves toiled in the blazing sun to build this symbol of absolute power and vanity.
to long

About 20 to 23 years is educationally estimated The pryamid of Giza

The great pyramid of Giza is called also called Pyramid of Khufu, It's known as the pyramid of Khufu because he built the Pyramid of Giza. The pyramid of Giza is also the largest of the three pyramids in Giza, there are three known chambers inside the pyramid of Giza. The great pyramid of Giza was built by the fourth dynasty. They built the pyramid of Giza out of limestone. They built the pyramid of Giza because the Ancient Egyptians believed that their pharaohs were gods so they built tall pyramids to help them into heaven. It took 20-25 years to build the pyramid of Giza.
It is estimated that it took about 20 years to build the great pyramid of Giza .This is an estimate based on historical records of the time including markings left in the actual tomb.Some historians believe it may have taken as little as 14 years. What we do know is that the 3 great pyramids of Giza were built between 2575 BC abnd 2465 BC giving a time frame of 110 to complete all 3.Egyptologists now believe that these pyramids were not constructed by slaves but will workers intent of showing devotion to the pharoah, a living god thus making sure they were would be favourably rewarded in the "After-life"
It took 14 to 20 years and 100,000 naked slaves to build Khufu's pyramid
It took between 14 and 20 years
about twenty years

People who say that have never read the Holy Quran. How can a Holy book which preaches that the value of each single Human life is as important as the entire mankind can be a terrorist training manual? Holy Quran makes it very clear in the following Verse.

Surah 5 (Chapter 5) Al Maida Verse: 32

"Whosoever killeth a human being for other than man slaughter or corruption in the earth, it shall be as if be had killed all mankind, and whoso saveth the life of one, it shall be as if he had: saved the life of all mankind."

This is the preaching of the Holy Quran, if someone kills even a single innocent human being he/she will be punished by Allah for a punishment of that equivalent to killing the entire mankind on the Last Day and he will be sent into the Hell fire.

Islam is a religion of Peace, even the very name of this religion "Islam" means peace.

The above verse is taken from Pickthall's translation of the Holy Quran, a pdf version is available on the internet on the following website, if you wish to verify what I have said here.

http://muslim-canada.org/pickthallquran.pdf

Imaam Ja'far as Saadiq (as) - the 5th Isma'ili Faatemi Imaam has said to his assembly members that, 'Qur'an has 7 meanings, 70, 700, 7000, 70000 meanings'. Qur'an is the word of Allah. No mankind can understand it as he is the creation of Allah and the creation is always inferior to the Creator. Qur'an - in modern understanding - is in the encrypted form. As Rasoolullaah (saws) has said that what you recite as the Qur'an is the Zaahir (evident) of the Qur'an the book itself is Silent. Allah has glorified and ascended us with the true interpretations of the Qur'an. Me and my progeny are the inheritors of this true interpretations which is the Baatin (secret) of Qur'an. Holding only Qur'an - the Zaahir, will not help you and you will deviate from the right path. O the people of my ummat, said Rasoolullaah (saws), hold the Qur'an and my Ahl ul-Bayt (as) - the Zaahir and Baatin of the Qur'an - and you will never deviate from your destiny. My Ahl ul-Bayt (as) is Maulaana 'Ali (as), Maulaatana Faatema (as), Imaam Hasan (as) and Imaam Husain (as) and the Imaams from the progeny of Imaam Husain (as). == == The quran is not terrorist training manual. People misinterpret the text from original the Arabic text to different languages which mixes some of the words up. Mostly because they know most non-muslims have never read it.Read the Qur'an for yourself and decide for yourself.