Only a few hours passed between when architect Andrea Serboli toured his apartment and when he signed the forms to buy it. “In recent years, the real-estate market in Barcelona has gone crazy, so it forces you to make quick decisions,” he says. “But from the first moment, this apartment made me realize that we liked each other.”

The small circular window that butts into the backsplash provides natural light in the bathroom.

Maybe sparks flew fast because of the setting. The apartment is perched above a tree-lined passageway leading to the Sagrada Familia ; the church's spires can be seen from the balcony. Plus, the building itself was built in 1914, and reflects the city’s famed Catalan Art Nouveau architecture. These details made it easy for Andrea to look past the home's classic modernist layout, which divided the property into six rooms, as well as the years of neglect that had allowed most of the historic elements to crumble. To Andrea, this apartment was an opportunity to create something new—and to take up the interesting role of being his own client.

A Mags sofa by Hay sits in the living space next to a Zig Zag pouf by Kettal . The artwork is by Piero Serboli .

“It's easier when the roles are reversed because the evolution is more linear. When you have a client, you have to make them feel like you have a clear idea,” he says. “But making a home for yourself is like making a sketch. If it were not for the limits of the budget and the patience of the suppliers, you could be constantly changing it.”