After years of inaction, Downtown Crossing's canyon may be filled. The site's new developer has proposed a 606-foot tower for the site, reports the Boston Herald. Millennium Partners detailed a $615 million project to fill in the massive hole that once was a Filene’s department store.

The  proposed 54-story Millennium Tower will include 500 residential units, 230,000 square feet of retail space, 200,000 square feet of office space and 525 underground parking spots, according to the Boston Business Journal. The living space will be in the tower, while the retail space will occupy the lower levels and the office space will be at the top floors.

At 606 feet, the Millennium Tower would be the fourth tallest building in the skyline after the Hancock Tower, the Prudential Tower and the Federal Reserve building. Millennium Partners expects their environmental impact study to be ready for public review within the next 60 days.

This project is expected to begin at the end of next year, after Millennium Partners finishes their restoration project of the 1912 Burnham Building, which housed Filene’s.