Pieter Adriaan Jacobus "Piet" Moojen (26 June 1879 - 1 April 1955) was a Netherlands-Indies architect, painter and writer.

[1] As a member of the Commisie van Toesicht op het beheer van het land Menteng, Moojen was influential in designing the town planning for Batavia's Nieuwe Gondangdia Garden City (now Menteng).

van der Meyl underscored Moojen's importance to the emergence of Modernism in the Dutch East Indies.

Berlage made similar comment in his Mijn Indische reis (Rotterdam 1931).

He reasons that in designing the Batavia's NILLMIJ office and Kunstkring Art Gallery, Moojen replaced the customary Classicist forms with "the realization of a more rational concept", an international architectural movement known as Rationalism, which was later dubbed as New Indies Style to refer this movement in the Dutch East Indies where it was slightly conformed to suit the local climate.