He was a renowned painter, sculptor and architect who worked in Italy and Spain during the Spanish Renaissance. He lived in Toledo in central Spain from 1577 until his death. This city is represented in his famous painting View of Toledo, or Vista de Toledo in Spanish.
There are various reasons as to why this is included in El Greco's most notable paintings. Firstly, View of Toledo is one of only two surviving landscapes by El Greco. In fact, it is considered to be the greatest of the two. The scarcity of landscapes in his collected could be due to the fact that they were rarely painted during the Spanish Renaissance. During this time, landscape paintings were banned by the Council of Trent as they were not seen as suitable subjects for paintings.
El Greco was born Domenikos Theotokopoulos (1540-1614) but received the nickname "El Greco", which means "The Greek", because of his Greek origin. This painting is also considered to be the first ever Spanish cityscape because it depicts buildings along with the landscape. Some art historians believe El Greco therefore invented the genre of cityscape, making View of Toledo an example for all who have painted in this subject since El Greco's time and for all those who ever will.
The painting is also so admired and famous because of it's beauty. The way El Greco painted the sky is considered to be among the best representations of the sky in Western art. It has been compared to Van Gogh's The Starry Night, which was painted around 300 years later. The use of contrast between the dark sky and the brilliant green hills is also admired. The way the landscape is painted is also part of the idea of mysticism that was popular during El Greco's career.
Mysticism involves the concept that everything is under the influence and mercy of God who may not actually be that merciful. The dominating and ominous sky creates a sense of danger and vulnerability for the city below. Art historians consider this painting to represent El Greco's idea that the world outside can be dangerous and how there are more powerful forces than we can sometimes see.
A third reason for which View of Toledo is so famous is because El Greco took liberties with the layout of the city upon the hill. This was also uncommon for artists during his time. El Greco rearranges some of the buildings that make up Toledo's cityscape with the exception of the Castle of San Servando on the right. El Greco added in the cathedral with the large steeple to this view of the city and moved it beside the royal palace of Alcazar.
This liberty of representation shows that accuracy was not El Greco's intention and supports the notion that View of Toledo is more so a representation of his beliefs about mysticism. The city becomes emblematic or symbolic rather than an actual geographical location. In this way, and in the other points mentioned above, El Greco's View of Toledo was well before it's time and immensely influential since.