The $275 million Austonian, a luxury condo tower at Congress Avenue and Second Street that will be the city's tallest building when it rises to 56 stories - celebrated its halfway mark (the pouring of the 28th floor ) last night with a party on the 19th floor.

An invitation-only crowd of more than 400 was treated to spectacular views of the city from all directions, as they sipped wine and noshed on hors d'ouevres while members of the Austin Symphony played.

(And, voyeurs with a zoom lens also could have read the paperwork lying on people's desks in the 100 Congress office building directly south).

Though the space wasn't finished, the views from the floor-to-ceiling windows were the main attraction anyhow. Landscape architects for the project said the 683-foot tower, once completed in early 2010, will be visible from Buda.

Marshall and Jennifer Jones, who now live in the 5 Fifty Five luxury condos atop the Hilton Austin downtown, are contemplating purchasing in the Austonian.

"It's brilliantly designed, the amenities are second to none, and you cannot beat the location," Marshall Jones said.

They especially like the fact that the top two floors, which will include a private dining room, kitchen area, fitness club and other amenities, will be available for use by anyone in the building.

"We're doing our due diligence," Marshall Jones said, adding that he expects the couple could sell their current condo (purchased in March 2005) next year and make a profit.

Austonian units are priced from $573,000 to more than $7.2 million.

Meanwhile, Daniel Woodroffe and Eric Schultz with TBG Partners, the project's landscape architects, say they are designing a unique, street-level landscape feature.

"We've got great ideas for the streetscape of the project," said Woodroffe, a principal with TBG, Texas, largest landscape architecture firm whose projects include Town Lake Park and the Hyatt Lost Pines Resort near Bastrop.

The Austonian is being developed by Benchmark Development, which has been developing communities in Austin for nearly 20 years. The financial backer is Benchmark's parent, the Spanish company Grupo Villar Mir.