The stalled NorthPoint project, which is already reeling from a nasty legal battle between its partners, now faces another serious blow that could lead to delays in the opening of condo high-rises.
Contractors who had been working on the multibillion-dollar city within a city have taken out liens on the Cambridge development, saying they are owed more than $1.5 million for work they were never paid for.
The liens could prevent Boston and Maine Corp., a NorthPoint landowner and lead developer, from pushing ahead with plans to open the project’s first two …

