“If we were really similar, we wouldn’t be able to work together. We push and pull each other in different directions.”

Beirut is a city of past and present. Its downtown juxtaposes modern towers against Roman ruins. Low-rise edifices from the Ottoman and then French rule of Lebanon remain, some of them hulled out—visible bookmarks in the city’s long history that attest to a devastating war from 1975 to 1990.

Against the backdrop of Beirut’s culture and history, Tessa and Tara Sakhi, young globetrotting sisters, founded T SAKHI in 2015. The architecture firm seeks to mirror their hometown’s hybrid identity, incorporating the myriad aesthetic traditions of Lebanon with their internationally minded scope on modern design.

Tessa, 25, and Tara, 27, diverge markedly in disposition. “Tara is more the artist,” says Tessa, as the two sit side by side on a couch in their studio. “If we were really ...