Ernst May (July 27th 1886 - September 11th 1970) was a German architect and city planner.

May successfully applied urban design techniques to the city of Frankfurt am Main during Germany's Weimar period, and in 1930 less successfully exported those ideas to Soviet Union cities, newly created under Stalinist rule. He had to leave the Soviet Union when Stalin's regime grew ever more hostile to foreign white collar workers. Thereafter May spent many years in African exile before returning to Germany near the end of his life.

May was born as the son of a leather goods manufacturer. His education from 1908 through 1912 included time in the United Kingdom, studying under Raymond Unwin, and absorbing the lessons and principles of the garden city movement. He finished a study at the Technical University of Munich, working with Friedrich von Thiersch and Theodor Fischer, a co-founder of the Deutscher Werkbund.

Working for himself and others through the 1910s, in 1921 he helped win a competition for rural housing estate developments in Breslau. His concepts of decentralized planning, some of which had been imported from the garden city movement, he won the job of city architect and planner for his home city from 1925 through 1930. Working under Mayor Ludwig Landmann, the position gave him broad powers of zoning, financing, and hiring. There was copious funding and an available labor pool. He used them.

In the context of a housing shortage and a degree of political instability, May assembled a powerful staff of progressive architects and initiated a large-scale housing development program. May's developments were remarkable for the time for being compact, semi-independent, well-equipped with community elements like playgrounds, schools, theatres, and common washing areas. For the sake of economy and construction speed May used simplified, prefabricated forms. These settlements are still marked by their functionality and the way they manifest egalitarian ideals such as equal access to sunlight, air, and common areas. Of these settlements the best known is probably Romerstadt, and some of the structures are colloquially known as Zickzackhausen.

In 1926 May sent for Austrian architect Margarete Schutte-Lihotzky to join him in Frankfurt. Lihotsky was a kindred spirit and applied the same sort of functional clarity to household problems, and so in Frankfurt, after much analysis of work habits and footsteps, she developed the prototype of the modern installed kitchen, and pursued her idea that "housing is the organized implementation of living habits".

May's Frankfurt was a civic and critical success. This has been described (by John R. Mullin) as "one of the most remarkable city planning experiments in the twentieth century". In two years May produced more than 5,000 building units, up to 15,000 units in five years, published his own magazine (Zeitschrift Das Neue Frankfurt) and in 1929 won international attention at the Congres International d'Architecture Moderne. This also brought him to the attention of the Soviet Union.

In 1930 May took virtually his entire Frankfurt staff to Russia. May's group amounted to a task force of 17 people, including Lihotsky, her husband Wilhelm Schuette, Arthur Korn, the Hungarian-born Fred Forbat, the Swiss Hans Schmidt, the Austrian-born Erich Mauthner and the Dutch Mart Stam. The promise of the "Socialist paradise" was still fresh, and May's team and other groups of western planners had the hope of constructing entire cities. The first was to be Magnitogorsk. Although May's group is indeed credited with building 20 cities in three years, the reality was that May found Magnitogorsk already under construction and the town site dominated by the mine. Officials were indecisive, then distrustful, corruption and delay frustrated their efforts, and May himself made misjudgements about the climate. May's contract expired in 1933, and he left for British East Africa (Kenya). Some of his architects found themselves unwanted by Russia, and stateless.

The 1995 documentary film Sotsgorod ("Socialist Cities") interviewed some of the last survivors of these groups: Lihotzky, Jan Rutgers, and Phillipp Tolziner of the Bauhaus Brigade, and visited four of the planned cities: Magnitogorsk, Orsk, Novokuznetsk and Kemerovo.

May worked, farmed and completed some architectural work in Kenya, then returned to Germany after the end of World War II. From 1954 through 1956 he led the planning department in Hamburg, was involved in several large housing projects in other cities, and died in 1970.