World Trade Center tower to surpass Empire State (CBS/AP) On Monday, the new One World Trade Center is due to reach and surpass the height of the Empire State Building, to become New York City's tallest building. Workers will be putting steel columns in place that will make the unfinished frame of the building a little more than 1,250 feet high - the level of the Empire State Building's highest observation deck. The tower still isn't as high as the antenna that sits on the Empire State Building. Experts usually don't count antennas or flagpoles when measuring building height. The "Freedom Tower" isn't expected to reach its full height for at least another year. When complete, One World Trade will stand at 1,776 feet (which includes a 408-foot-tall antenna spire that will sit on its roof). Discounting the antenna, it will still be the second-highest building in the U.S., after the Willis Tower in Chicago. The Port Authority of New York and New Jersey said it will mark the milestone at 2 p.m. Mayor Michael Bloomberg told CBS Station WCBS it has been a collaborative effort: "Lots of people deserve credit, it's taken a long time. But this is probably the most complex construction site any place, ever. Completed in 1931, the Empire State Building was the tallest free-standing structure in the world until 1967 (when Moscow's Ostankino Tower was completed), and lost its status as New York City's tallest building when the original World Trade Center (at 1,368 feet high, plus a 359-foot antenna) was completed in 1972. Now it is being demoted again. As the new World Trade Center claims bragging rights for the city's tallest, the New York Post reports that on Monday night the tower will be lit up blue-and-white, characterizing the color scheme (according to unnamed sources) as a pointed dig at the Empire State Building's controversial rejection in 2010 of illuminating the building in honor of the 100th birthday of Mother Teresa. The Empire State Building's owners declined comment, and instead told the Post, "The world's most famous office building, the ancestor of all super-tall towers, welcomes our newer, taller cousin to the skyline."