The Boston Redevelopment Authority just put out the formal call for proposals for redeveloping the city-owned Winthrop Square Garage in the Financial District. Per Tim Logan at the Globe, the BRA is looking an "iconic ... innovative" tower that could run to around 700 feet high, immensely tall for Boston and just under the limit the Federal Aviation Administration mandates because of nearby Logan Airport (no relation).

Eight developers and development teams have already proffered ideas for the garage, and, given the formal request, the BRA now expects more to filter in, including updates of the original eight. This octave gives a good sense of the sheer scope of any Winthrop Square development. Let's dive deep:

Millennium Partners, they of the game-change-y Millennium Place and Millennium Tower (Millennium!), pitched a 750-foot spire with 360 residential units and 14 floors of office space as well as 41,000 square feet of retail, including a market arcade.

Thomas O'Brien, a former director of the Boston Redevelopment Authority, would turn the garage site into a public plaza and then build a 780-foot tower with 700 apartments and condos across the street in a deal with the Franciscan friars who run St. Anthony Shrine Church. O'Brien would also build a public school. (For comparison's sake, know that the Hancock is 790 feet high.)

780-foot tower with 700 apartments and condos across the street in a deal with the Franciscan friars who run St. Anthony Shrine Church. O'Brien would also build a public school. (For comparison's sake, know that the Hancock is 790 feet high.) Accordia Partners would build a 750-foot building with 140 condos, a public gallery, retail and a 275-room Le Meridien hotel (it would join the one near M.I.T. in Cambridge).

A team that includes Hudson Group North America, developer of downtown Boston rental Radian, proposed another 750-foot tower, with 156 condos, 288 apartments, a 300-room hotel, public space and retail.

Trinity Acquisitions would build a 51-story building with 276 hotel rooms, 328 apartments and 261 condos.

The Fallon Co., which is behind so much of the recent construction in the Seaport District, pitched two buildings connected by a podium. One would be 75 feet and contain apartments; the other would soar to 700 feet, with 32 floors of apartments and 18 of condos. There would also be an open retail concourse.

Steven Belkin of Trans National Properties, who once proposed a 1,000-foot tower at the site (yup), is back with a 740-foot pitch now. It would include apartments as well as 100 condos (built by McMansion kingpins the Toll Brothers). There would also be a retail galleria; an "Innovation Sculpture Park"; and an "Innovators Walk of Fame." Belkin would also build on an adjoining site he owns at 133 Federal Street.

Finally, Lincoln Property Co. would build a 47-story tower with 29 floors of offices, a hotel with at least 250 rooms, six floors of condos and retail.

Developers have six weeks now to pitch the city. Stay tuned.