Today is the feast of St James the Greater, known in Spain as Santiago el Mayor. His tomb in Compostela in the Northwestern region of Galicia has been an important pilgrimage site for well over a thousand years -- as important in the Middle Ages as Rome and Jerusalem. A bit of information: his story from the Golden Legend in Caxton's translation, and an interesting interactive site from UCLA on the Way of St James.
Imagine what it's like when weary pilgrims who have been walking for weeks under the unforgiving Spanish sun arrive at the Cathedral at Santiago de Compostela. Imagine how meaningful it is to them! Imagine how bad they smell! You need a lot of incense to cover that up, hence the Botafumeiro: