In the seaside town of Sesimbra, just 24 miles south of Lisbon, resides the charming Chapel of Espírito Santo dos Mareantes (Chapel of the Holy Spirit of the Navigators). Founded by a confraternity of local seafarers and fishermen sometime during the late 14th-15th centuries, the religious sanctuary also included a hospital and meeting space underneath.

On this lower floor, poor and sick sailors were given succor. While convalescing or conversing, several of these maritime men drew pictures of boats on the walls, vessels they were most likely familiar with and which may have been anchored just a short distance from the chapel. 

Of the six charcoal drawings found during excavations of the building in the early 1980s, only a couple are clearly visible today. One of the surviving sketches depicts, according to naval archaeologists and historians, an English galleon and may hint at the Battle of Sesimbra Bay, where the British fought with Spanish forces in 1602 during the period that King Philip II of Spain ruled Portugal.

Now a museum, informational panels downstairs state that the former prisoners-of-war held by Muslim forces, probably in North Africa, were given special holistic attention. Coincidentally, one ship drawing with an actual date (1546) portrays a flag with what looks to be stars and a crescent, similar to the present-day flags of Algeria and Tunisia.