New York, Jan. 5. - The most valuable piece of real estáte ever ofïered at auction in this city was sold Honday. The property was the new flfteen-story sky scraper, the Syndicate building, at the southwest corner of Nassau and Liberty streets. It was sold under foredosure of the fourth mortgage of $900,000, subject to the prior mortgrages aggreg-ating ?2, 000,000. The interest on the mortgage foreclosed is not overdue and the parties in action say that the guit is a friendly one. The foreclosure was made under the ten-day tax clause. The fourth, or $900,000 mortgage, was held by Benjamin H. Losey, as trustee for the members of the Syndicate Bealty company, the carpenter, mason and plumber who furnished the materaal and work for the construction of ttie building and is almost wholly wiped ut by the sale. John W. Golding, f-r a cliënt whose name he would not give, bought the building for $2,508,219.58.