This coat of arms probably originates from the town Refinery, or Saltpetre house, which was built in 1647 and stood on the corner of the Palmgracht and the Lijnbaansgracht. Saltpetre was used to make gunpowder, and was imported from South America, China, India and Spain. Amsterdam was an important trading market and depot for saltpetre. The crosses take the form of the numeric symbol X; the apostle Andreas is said to have died on such a cross. It has been suggested that the three crosses stood for the three enemies of old Amsterdam: flood, fire and pestilence. In 1489 Maximilian of Austria granted Amsterdam the right to place the royal crown above its civic arms, as a gesture of gratitude for the city’s financial and military aid. The people of Amsterdam were very proud of this fact, and even placed the crown atop the tower of the Westerkerk (West Church).