The term "vanity project" is having a moment.

It tends to surface whenever US President Donald Trump floats another plan to give Washington, D.C. an architectural — and costly — facelift.

Whether it's a $100-million triumphal arch , a billion‑dollar White House ballroom or a $13-million redesign of the Lincoln Memorial Reflecting Pool, each proposal revives the questions: What counts as a political vanity project, and why do leaders pursue them?

Trump's latest D.C. project: Repainting the floor of the Lincoln Memorial Reflecting Pool 'American flag blue' Image: Olivier Douliery/abaca/picture alliance

Distinctive features of vanity projects

First, not every expansive or expensive endeavor — across eras or countries — counts as a vanity project .

Esra Akcan, professor of architecture at Cornell University, says that while architecture often fulfills multiple and sometimes competing practical, social, governmental and symbolic needs — making definitions of the concept of "vanity project" inherently blurry…