Flood of visitors expected at Ark Encounter opening on July 7 in Williamstown, Kentucky

A view of the Ark Encounter in Williamstown, Kentucky.(Facebook/Ark Encounter)

Ken Ham's gigantic Ark Encounter will open in Williamstown, Kentucky on July 7 with thousands of visitors expected to marvel at the largest timber frame structure in the world.

The ark is a replica of the biblical Noah's ark with a length of 510 feet, width of 85 feet and a height of 51 feet. It was built at a cost of $102 million.

Ham told The New York Times that he built the ark to advance Christianity.

"The reason we are building the ark is not as an entertainment centre," he said. "I mean it's not like a Disney or Universal, just for anyone to go and have fun. It's a religious purpose. It's because we're Christians and we want to get the Christian message out."

In the Bible, God sent a flood in Noah's time to wipe out morally corrupt people. The ark serves as a reminder that God will put an end to those who oppose the Bible and support abortion, atheism and gay marriage, the New York Times says..

"We're becoming more like the days of Noah in that we see increasing secularisation in the culture," Ham said.

The atheist group Tri-State Freethinkers is planning to hold a protest against the Ark Encounter on opening day.

It tried to place billboards on the highway approaching Ark Encounter, calling it the "Genocide and Incest Park," but was rebuffed by billboard companies.

"The moral of the flood story is horrible," said Freethinkers' president Jim Helton. "We're not saying he can't build his park. But we don't think it's appropriate for a family fun day."

Ham said he expects the Ark Encounter to attract 1.4 million to 2.2 million visitors in the first year and help double the attendance at the nearby Creation Museum.

Workers have also been preparing exhibits for the ark. According to young-earth creationists, the ark carried up to 1,400 kinds of creatures.

But there will only be 30 pairs of stuffed animals on the Ark Encounter due to space limitation.

"We have to have dozens and dozens of bathrooms for visitors. Noah didn't have to have that," said Tim Chaffey, content manager of Answers in Genesis ministry.

Ham railed against atheist groups that are trying to prevent the Ark Encounter from getting state tax incentives.

Judge Greg Van Tatenhove of the U.S. District Court for the Eastern District of Kentucky ruled in favour of the ark, saying tourist attractions like Ark Encounter meet the general criteria for tax incentives.