The most beautiful tiles in Lisbon are not in majestic palaces or soaring cathedrals. They decorate humble subway tunnels and ordinary streets like Infante Santo.

Keil do Amaral, the architect who designed the subway in the late 1950s, was dismayed that there were no funds budgeted to cover the bleak cement walls. His wife, the painter Maria Keil, suggested the use of inexpensive tiles and offered to design them for free.

Keil filled the subway with elegant modernist tiles that brought the art of tile making into the 20^th century. She continued, throughout her life, to dress the walls of the city with tiles that make Lisbon feel young and pretty. If you’re visiting the capital, here’s a challenge for you: how many of Maria Keil murals can you find?