Federal Realty Investment Trust and Merlin Entertainments today announced plans to open a Legoland Discovery Center at the Assembly Row development in Somerville.

The indoor amusement park will be built in the same section of the development as the previously announced movie theater.

The attraction will open in late spring 2014. It will be the first-ever Legoland Discovery Center in Massachusetts and the only one in the New England region.

Based on the popular children’s toys, Legoland Discovery Centers are an amusement parks with Lego-themed rides, a 4D cinema, an interactive LEGO Factory Tour experience that shows visitors how the plastic bricks are made and a range of themed play areas.

Assembly Row’s Lego Miniland exhibit – an exhibit found in every Legoland Park that highlights iconic buildings in each park’s location -will include the Prudential Tower, Quincy Market and more iconic Boston structures nominated by the local community.

Plans and designs are already being drawn up for the 44,000 square-foot space and construction is expected to begin this fall.  Lego models for the Assembly Row attraction will be made in Merlin’s specialist studios around the world and shipped in during construction, ready for the opening in 2014.