Architecture Foundation Director Rowan Moore has resigned to focus on his writing career.
Moore, who has been director since 2002, is also the architecture critic for the London Evening Standard newspaper.
He says he will remain in the post until mid-June and then contribute part-time during a transition period.
He now plans to focus on his writing career including an expanded role at the newspaper.
"This is a good time for someone new to take over and lead the Architecture Foundation to its next stage," he says.
"Our position in terms of programme and funding is strong, and makes a good base for developing new ideas."
By Elizabeth Clifford-Marsh