The Chicago Plan Commission on Thursday signed off on a pair of projects with a combined, $700 million price tag: one filling a surface parking lot near Holy Name Cathedral, the other triggering a development boom in the North Branch Corridor.

The twin-tower complex known as “One Chicago Square” will include 869 residential units at a cost of $500 million.

It will become Chicago’s 6th-tallest building – nearly as tall as the Hancock Building – filling a parking lot owned by the Archdiocese of Chicago at the corner of State Street and Chicago Avenue.

Both towers will rise from a nine-story commercial base.

Roughly 225 of the development’s 1,090 parking spaces – none of which would be visible from the street – would be reserved for use by Holy Name parishioners.

Instead of building affordable units on site, JDL Development will make a $6.1 million payment that will bankroll construction of 22 affordable units at the Lawson House SRO development across the street.

JDL will satisfy the remainder of its city mandate by making the largest payment ever made to Chicago’s Affordable Housing Opportunity fund: $11.3 million.

That’s on top of a $13.2 million contribution – the second-largest bonus ever paid – to the so-called “Neighborhood Opportunity Bonus Fund.”

The share the wealth fund was created by Mayor Rahm Emanuel to rebuild neighborhood commercial corridors with contributions from developers allowed to build bigger and taller downtown projects.

Planning and Development Commissioner David Reifman credited JDL with devising a “great creative approach” to Chicago’s affordable housing mandate.

“They’re not doing affordable housing on-site, but it works well for us because the Lawson YMCA…is a very important SRO. We’re looking for sources of funding to make sure that project can work. So, it’s a great synergy. The location is ideal. It’s right down the block,” he said.

Reifman argued that concerns about adding density to an already congested area will be mitigated by a host of traffic improvements negotiated by local Ald. Brian Hopkins (2nd) and bankrolled by JDL aimed at remedying what the alderman has called a daily “traffic gridlock nightmare” on Chicago Avenue.

That includes a host of traffic signal improvements, removal of parking lanes, the addition of left-turn and right-turn arrows and the return of articulated buses to the area.

“It’s right by the Red Line, the Chicago Avenue stop. It’s a major transit-oriented development. I don’t think it’s too much. It’s a beautiful building. It’ll be a real asset architecturally. It’s not that overwhelming a number of units for the area,” Reifman said.

The Plan Commission also signed off on a $200 million commercial building – with 4.5 acres of open space and a picturesque walkway along the Chicago River – on a site owned by Tribune Media at 640-to-740 W. Chicago Ave.

As many as 6,000 people could ultimately work and 800 of them could live on the massive riverfront development triggered by Emanuel’s plan to open 760 acres of protected industrial land to residential and commercial use in the North Branch corridor.

But Tribune Media and its partner, Riverside Investment and Development, will have to return to the Plan Commission for approval of subsequent phases.

Riverside will pay the city a $1.1 million “Industrial Modernization Fee” for the right to convert five acres of previously protected land to non-industrial uses.