Martin Luther King's memorial has awed visitors as it opened  for a public preview at the National Mall in Washington on Monday ahead of Sunday's official dedication ceremony 

The 30-foot granite statue of the slain civil rights leader is the first person who didn't serve as president of the U.S. to receive a major memorial on the mall, which is surrounded by monuments and memorials honoring presidents George Washington, Thomas Jefferson, Franklin D. Roosevelt and Abraham. The idea for the King memorial was proposed about 27 years ago, according to CBS News.

It will be dedicated on Sunday, 48 years after King led the 1963 March on Washington and delivered his famous I Have a Dream speech.

At the new memorial, King is depicted standing with a scroll of papers in his hands. An inscription on at the sculpture reads: Out of the Mountain of Despair, a Stone of Hope.

The monument is what it is, says King's son Martin Luther King III in an interview with NPR. It can inspire, it can encourage. But we, through other organizations, have to continue this massive body of work. My dad talked about eradicating poverty, racism and militarism. We've made strides in race - great strides - but when you look at poverty and militarism in terms of expenditures, we've probably made very little progress. And unfortunately, poverty is growing, so there's still a huge body of work that has to be done.

A 450-foot wall full of inscriptions includes some of King's most famous lines including, We shall overcome because the arc of the moral universe is long but it bends towards justice.

Visitors of the memorial will be able to enter through the two pillars that depict the Mountain of Despair. Both displays were built on 150 blocks of granite.

Some critics have said that the statue doesn't look like King, according to CBS News. But Harry Johnson, president and CEO of the Memorial Foundation, said they chose the best sculptor for the project.

Alluding to a famous King speech, Johnson said Dr. King himself said you shouldn't judge a person by their skin but by the content of their character, and in these terms we're talking about this man's artistic character.

The display was created by Lei Yixin, who holds the title of master sculptor in his native China, where most of the work was done, CBS News said.