Every year in Paraguay the 15th August is one of the countries largest and most important national holidays. It marks the anniversary of the founding of Asunción.

On the 15th August 1537 Juan de Salazar y Espinosa would have been quite unaware that the settlement he was about to found after turning his ship off the River Paraguay and into the Bay of Asunción would grow into the capital of an independent nation and survive as one of the oldest permanent cities in the whole of South America. 
The expedition had not left Buenos Aires as a mission of conquest seeking to expand Spanish control further up river, but instead as a search party to find the ship of previous adventurer who had failed to return. 
This was Juan de Ayolas who had headed up river to chart and explore the land. He may have been the first Spaniard to see the Bay of Asunción, but his ship was never found, so what he had seen was lost with him. 
It was after heading far up stream on his search that Salazar turned around to return to Buenos Aires, abandoning all hope of finding Ayolas. It was whilst on his way back that the bay was spotted and Salazar pulled into it to see if it would make a suitable place for a settlement and whether the locals would be any less hostile than the Pampas Indians surrounding Buenos Aires.
To his delight he found a wide sheltered bay which would make an ideal harbour and a shore which was well suited to placing a harbour upon. 
There were, as expected local people already living in the area. They though were of a far less militant nature than the one he had left behind. 
After the usual introductary skirmishes the indians headed back to their settlement on top of the nearby Lambare Hill. From their rather than renewing attempts to drive the Spanish back to their ships a truce was called with a number of women being sent to the Spanish camp as a peace offering. The gifts were accepted and further hostilities avoided. 
Once a camp was made and peace established a name was needed for this new settlement. With it being the Day of the Feast of Our Lady of the Assumption the grand name of Nuestra Señora Santa Maria de la Asunción was chosen by Salazar. Fortunatly over the years this became shorterned into the much more managable Asunción. 
Asunción also through the course of time aquired another title. Mother of Cities. This refects both it’s age and the number of other settlements founded from it. 
There was then just one final chapter in the foundation of Asunción. In 1542 the Pampas Indians finally through the Spanish out of Buenos Aires, burning it to the ground in the process. From this wreckage many survivors headed up river to Asunción and with their arrival began the process of turning a small riverside settlement into a city of importance.