Lower Manhattan's Verizon building isn't just marring the skyline - it's also much bigger than it's supposed to be, a lawsuit charges.

The building is actually one-third larger than allowed, a city agency claims - but no one noticed for 31 years.

The city's Educational Construction Fund filed a suit alleging it sold Verizon construction rights for a 771,003-square-foot building in 1972.

But in 2007, when Verizon sold much of the building to developers who promised to turn it into a gleaming glass office tower, the company bragged the structure contained a whopping 1 million square feet of space - far more than Verizon had paid for.

"People started saying, 'Wait a minute, these numbers don't add up,'" said Lawrence Bartelemucci, a lawyer for the fund, who noted it was never able to enter the building to measure the square footage.

The fund is suing Verizon and the developers for fraud, breach of contract and unjust enrichment, seeking $53 million plus interest and a court declaration that the proposed renovation would be illegal.

Read the full story: New York City sues Verizon for too-big building