With its big windows and light-filled sanctuary, the ossuary in Faro may be one of the cheeriest buildings made of human bones you’ll encounter.

The inscription over the door reads: “Stop here and think of the fate that will befall you – 1816,” a helpful reminder put in place by the Carmelite monks who built the chapel that year on the grounds of the larger church dating to 1719.

It is not merely decorated with bones — the walls are constructed from femurs with mortar. Skulls and other bones are placed on the interior at regular intervals, including grinning down from the barrel-vaulted ceiling, giving the place a pleasing, yet spooky, symmetry. The highlight of the ossuary is a complete skeleton covered in gold that hangs at the front of the chapel. The practice of moving bones from cemetery plots into ossuaries after a period of time in the ground (usually seven to ten years) was common throughout Catholic Europe until recently. The bones in this ossuary are the remains of 1,245 monks whose bones were displaced when the ossuary was built. There are several other bone chapels in Portugal, the most famous being in Evora.