Charles Fourier's design for a self-contained community and its building, housing a 'phalanx' of roughly 1,500 people (Britannica) on an agrarian-handicraft economy with shared halls, workshops and dining.
In more detail
The word combines phalange and monastère. Fourier planned voluntary work assigned by interest, pay scaled by how disagreeable a task was, and continued private property. He built none in Europe for lack of funds. In the United States Albert Brisbane's 'Associationism' inspired about fifty phalanxes, which lasted two years on average, by Britannica's count. Brook Farm began a Phalanstery in 1844; it burned down in 1846. Other accounts give 500–2,000 people for a phalanx.