422 West 42nd Street (between 9th / Dyer Avenues)
499-seat Off-Broadway built by the Schuberts as part of a residential development after they replaced the old Playwrights Horizons facility and demolished the Intar Theatre (420 W 42nd). The seating capacity is specifically catered to keep the facility within the maximum size for an Off-Broadway house specified in union contracts, thus avoiding considerably higher Broadway-level salaries for performers and crew.
In the 1970's the site was also apparently the home of the 42nd Street Cinema, a mercifully short-lived porn house.
Next: Douglas Fairbanks Theatre / John Houseman Theater