Sir Denys Lasdun; Modernist Architect Designed Royal National Theatre in London

Sir Denys Lasdun, a modernist architect who designed the Royal National Theatre in London, has died of pneumonia, his family announced. He was 86.

Lasdun, who died Thursday, was considered one of Britain’s leading architects. He once described his geometric designs as “the combination of the vertical and horizontal.” His buildings, with their interlocking levels and reliance on reinforced concrete, won him praise and criticism.

His most famous critic was Prince Charles, who condemned the Royal National Theatre on London’s South Bank as “a clever way of building a nuclear power station in the middle of London without anyone objecting.”

Born in London, Lasdun’s father was in the construction business and his mother was a pianist. Lasdun honed his craft with the Architectural Assn. School of Architecture but left before earning a diploma to work with architect Wells Coates, a leading proponent of modernist architecture. Lasdun served with the Royal Engineers during World War II before joining numerous architectural partnerships. He worked on housing projects and schools before venturing out on his own in 1959.

His first big commission was the Royal College of Physicians, which won international acclaim when completed in 1964.

Lasdun’s most famous design remains the Royal National Theatre, originally called the National Theatre, which the architect described as “an architecture without facades but with layers of building like geological strata, connected in such a way that they flow into the surrounding riverscape and city.”

Lasdun had to design a structure that could accommodate three theaters, one seating 1,100 people, as well as restaurants and bars. At the time, he likened the project to planning a small city. The entire project, from conception to its opening night, took more than 12 years.

Sir Norman Foster, whose projects have included the restoration of the Reichstag in Berlin, described Lasdun as “a pioneer, a world-class architect who had tremendous influence.”

Lasdun was honored with the title Commander of the Order of the British Empire in 1965 and was knighted in 1976. He was appointed a Companion of Honor in 1995.

Lasdun is survived by his wife and three children.