The Martin Luther King Jr. National Memorial, to be dedicated Sunday, is the first monument to a black leader on the National Mall, a landscape devoted to American cultural and political iconography.

In Philadelphia, there is no such memorial, to King or any other black leader, in Center City.

No African Americans have been favored with a place in the shadow of City Hall, which is nearly ringed by immense statuary of commercial, legal, and manufacturing moguls; generals from the Union Army; and a U.S. president.

In fact, until the All Wars Memorial to Colored Soldiers and Sailors was moved to the Parkway in 1994 from its hideaway in Fairmount Park, there was no prominent public art in Center City alluding to black life at all. Emancipation Proclamation Fountain by Gerd Utescher, installed in 1965, sits deep in a stairwell leading to the 15th Street SEPTA concourse, obscured by overgrown foliage and virtually invisible to passersby - as if to prove the point.

But with the opening in December of the memorial to enslaved Africans held by George Washington at the site of the President's House on Independence Mall, the obscure is becoming visible.

And in March, the city pledged $500,000 toward a proposed memorial to Octavius Catto, the abolitionist, civil-rights activist, and educator, gunned down on South Street in 1871. The piece would be installed at the southwest corner of City Hall, across the way from a memorial to President William McKinley, gunned down in Buffalo in 1901.

In effect, Catto would desegregate City Hall's monumental public art.

Rosalyn McPherson, who is managing the private $2 million Catto project, said the King memorial in Washington, the President's House (which she also managed), the Catto memorial, the African Burial Ground in New York, and other efforts under way around the country are evidence of an invigorated desire to acknowledge and understand the central place of African Americans in the nation's history.

"There's almost like a spirit of connect the dots," she said. "It's important. It's necessary. It's wonderful. And I don't care what it takes to get them built. What's important is that we're acknowledging these missing pieces."

That may be so, but in a city with a large and energetic African American population with a complex history, there is still a dearth of public art downtown that refers to that simple fact. According to a computerized inventory of city-owned public art, only eight of 650 pieces refer concretely to black life.

In addition, roughly 100 works of public art scattered about the city are by African American artists, commemorate the black experience, or honor prominent black figures, according to raw data provided by the Fairmount Park Art Association.

There is a memorial to the Philadelphia Stars and the Negro leagues at 44th Street and Parkside Avenue, for instance, installed in 2006, part of a memorial park.

And, in fact, there is a sculptural commemoration to King, the Freedom Memorial, with five bas-reliefs by Neil Lieberman and Paul Keene, on the grounds of 59th Street Baptist Church. The memorial, set in a space designed for contemplation, honors King and other slain civil-rights activists, along with John and Robert Kennedy and the four girls killed in the 1963 church bombing in Birmingham, Ala.

Such monuments and commemorations enhance their neighborhoods, but until the President's House project focused attention on downtown, there was a notable Center City void.

Penny Balkin Bach, head of the Fairmount Park Art Association, a private nonprofit devoted to public art in the city, said much public art became reality when a particular group decided it was important. The 2003 Irish Memorial at Penn's Landing, which began with Irish organizations and prominent Irish Pennsylvanians, is a case in point.

"The impetus or funding typically emerges from the community," said Bach. "It's a civic effort that starts with a group that wants to see it happen."

But the convoluted and grueling process of fund-raising, and navigating municipal procedures and regulations, can be daunting. Many public art proposals wither away mid-process, unable to make it to the finish line.

McPherson made the same point, saying the process is not only long but also not infrequently contentious. Within the African American community, "the culture of philanthropy has to be cultivated."

"We're often not even aware of the process of how money is raised," she said. "The process people go through is very complex"

The Catto project is supported by a multiracial group of business and political leaders, she said, adding that "individual dollars will come from prominent African Americans in Philadelphia."

If the memorial makes it to the finish line and takes a spot of honor on the apron of City Hall, it will fill a huge gap in the canvas of public art. Catto's life and death certainly prefigure King's, and the memorial will speak directly to dangers of freedom not yet attained.

That's a sober and challenging subject for public art, but a central one within the American experience.

Contact culture writer Stephan Salisbury at 215-854-5594, ssalisbury@phillynews.com, or @SPSalisbury on Twitter.