The heyday of the English landscape garden was the 18th century, and it stood for many things: the appreciation of natural beauty, of course, but also the idea of a civilized life, good taste, one's personal philosophy, and one's social status. Gardens also - though it is hard for us to credit - became expressions of their owners' political affiliations.
Until the picturesque style emerged as part and parcel of the Romantic Movement, gardens had been strictly formal, laid out with mathematical precision following the Italian and French examples. There then came a backlash against this rigid formality, led by, among others, the poet Alexander Pope. Pope and his allies argued for a more natural nature.
Lord Burlington was a major figure in the landscape garden movement, and he was famously influenced by his love of the Italian architect, Andrea Palladia, along with the picturesque or romanticized landscapes of Italian classical painting. With these in mind, he scattered his gardens and parks with classical Greek and Roman temples and statues. In other words, he wanted to make the garden look like those paintings.