Sailing the Horizon

500 Five hundred years ago, Portuguese and Spanish explorers wanted to discover unknown territories [this makes them greedy for new lands for their rulers] new lands. Magallanes and Elcano Magellen and Vasco da Gama [They are known as such in English speaking countries] (the first man to circumnavigate world) departed from Cadiz. It was the Age of Exploration for Iberic cultures. Cadiz, (southern Spain) was a important seaport and Seville (the interior city) also has a seaport.

Nowadays these seaports haven´t had the importance were not as important as in of the past.
At that time, there were a lot of many departing expeditions for the many regions of Africa. Most of them they had a singular skeletal crews...

I will shall continue this article if it is should prove interesting to you readers " :)

Sailing the Horizon

500 years ago Portuguese and Spanish explorers wanted to discover unknown territories. Magallanes and Elcano (the first men to circumnavigate the world) departed from Cadiz. It was the age of exploration for Iberic cultures. Cadiz (in the south of Spain) was a important seaport. Sevilla (an interior city) also had a seaport. Nowadays, these seaports are less important than in the past.
At that time, there were a lot of expeditions for many regions of Africa. Most of them had a singular crews..."I will continue if it is interesting" :)

*I'm not exactly sure what you mean to express in the last sentence, but I think it's along the lines of "Most of them only had one crew" 

*If this is for formal writing I wouldn't use "nowadays". You can replace it with "Today" to express "in current times".