Fenway Theater next to Fenway Park would open in late 2021 under latest proposal

Construction on a new theater next to Fenway Park could commence as soon as after the upcoming baseball season and wrap in the summer or fall of 2021, according to plans filed recently with the Boston Planning & Development Agency by an affiliate of the ownership group of the Red Sox and Fenway Park.

We’ve known since late September that the group had a big plan for a triangle of land where Ipswich and Lansdowne streets meet just beyond the famed ballpark. The filing provides the most details yet on it.

The theater would be a “state-of-the-art, multipurpose” performance venue with around 5,400 seats, according to the filing. It “is intended to fill a void in the landscape of performing arts venues in the greater Boston area by providing a facility whose capacity sits between venues that accommodate less than 2,500 patrons and the larger arena/stadium venues.”

The venue will host events year-round. And, to make room for it, the ownership group plans to relocate current service, loading, and receiving activities from the triangular space to newly constructed, off-street, interior loading dock bays within the Fenway Garage.

What’s more, mail and ground-slash-concessions facilities that also occupy the site will be relocated to within the ballpark or moved elsewhere.

The theater is still in what its backers call “the early design stages.” But, pending the necessary approvals, that construction could start once the Red Sox season wraps this year. The backers are hoping to complete most of the construction before the new Boston Arts Academy opens across Ipswich street. That is also scheduled for 2021. Stay tuned.