PHILADELPHIA They were told to make it better - Philadelphia's Art Commission would accept no less from architects designing a proposed $150 million museum devoted to the Revolutionary War. Especially one that would stand just two blocks from Independence Hall.

So Wednesday, Robert A.M. Stern Architects delivered. And they were rewarded with unanimous approval of revised designs they had put together for the Museum of the American Revolution at Third and Chestnut Streets.

The panel's vote effectively clears the way for building permits to be issued in the months ahead and for construction plans to be drawn up for a hoped-for opening in late 2016. Preparatory work for demolition at the site is slated to begin in about a week.

The firm went back to the drawing board after the commission, during a February meeting, found fault with its renderings, saying it did not feel all architectural components of the planned building fully blended with the surrounding historic district.

The changes that won over the commission were not minor: Architects replaced a cupola with a less-glaring, square-edged element lower on the building; reworked the front entrance on Third; and added to the facade on Chestnut a large lobby window and full-size bas-relief replica along the sidewalk of John Trumbull's famous painting hanging in the Capitol Rotunda, The Signing of the Declaration of Independence.

Museum president and CEO Michael Quinn called the commission's "unanimous" approval of the redesign "terrific news."

Asked how much the new elements would add to the project's cost, Quinn estimated hundreds of thousands of dollars. But this would be covered by funds set aside for contingencies, added spokeswoman ZeeAnn Mason, and would not change the budgeted price tag.

"Our team did a great job of responding to them," Quinn said in an interview after he and Stern partner Kevin Smith made presentations, and the commission approved the revised design.

"We really felt they were offering their comments in the spirit of achieving the best building for the City of Philadelphia," Quinn said of the commission's early feedback.

Art Commission director William J. Burke Jr. said the designers responded head-on to concerns that the original concept contained something of a "mishmash" of architectural styles. (The commission voted, 9-0, Wednesday in favor of the amended design.)

How unusual was it for a group to respond so on-point to the panel's recommendations?

"This particular group did it quite well," Burke said.

To reach this desired middle ground, the Stern firm held several face-to-face meetings over the last two months with commission members and museum officials, according to representatives for both.

And although one more commission vote is required, next month, to formalize the approval, the vote Wednesday effectively means the process of applying for building permits and preparing construction plans may proceed, according to CEO Quinn.

Fund-raising continues for the museum, which has received relatively little support from local foundations for fear it may cut into the business of existing museums in the city.

But in early March, main museum backer and $40 million donor H.F. "Gerry" Lenfest (part-owner of the company that owns The Inquirer) headlined a ceremony with former Gov. Ed Rendell at the planned site to begin what will be a busy year for turning the long-planned project into reality. (Another part-owner, Lewis Katz, also serves on the museum's board.)

Early-phase demolition work could begin in about a week, Quinn said, with the installation of a fence, followed by asbestos removal inside the long-vacant building that will be torn down to make way for the new museum: Independence National Historical Park visitor center, a structure built for the nation's Bicentennial.