The UK’s first purpose-built children’s theatre opens this week behind City Hall on London’s South Bank.

For the £14m Unicorn Theatre, Keith Williams Architects set out to make “a grown-up building for children”, where they can feel independent and be treated like adults. In the main 340-seat auditorium, raised above the entrance foyer to save space, the stage thrusts out into a double-decker amphitheatre of seating. “There is no division between actors and audience,” says Tony Graham, artistic director. “It is one space that allows the magic of theatre.” It was built by Mansell Construction Services with Theatre Project Consultants and Charcoal Blue as theatre consultants, Arup as structural and services engineer and acoustician, Buro Happold as access consultant and Bucknall Austin as cost consultant.