The park is a brain-child born from the inexhaustible imagination of Anton Gaudí, and it offers you the chance to take a break from the city's frenetic pace while enjoying stunning architecture immersed in a green setting.
As I have already said a few times, Gaudí never considered any of his works completely "finished". Everything was shaped and changed in time and space. The architect almost never made "designs": his phantasmagoric constructions usually started off from a graphic sketch, which was often just a scribbled "idea" that was more like a painting, which then took shape in the day-to-day work at the construction site.
Thanks to this ongoing evolution, some of his most ambitious creations have remained unfinished, as you have already seen here in Barcelona. Around 1900, once again at the request of his patron Eusebi Güell, Gaudí took on a great work, Güell Park, in a peripheral area of about 17,000 square meters to the city's northwest, at the slopes of Mount Carmel.
What you can visit today is a tiny portion of his urban project that included a real garden-city with sixty houses immersed in green, as well as a chapel, fountains, terraces, and other facilities. The project was implicitly opposed to the rigid structure of Eixample, the upper-middle class neighborhood which began construction after the mid-1800s and was practically devoid of gardens.
Today, the park is one of the preferred city destinations for both inhabitants and tourists alike, and is protected by UNESCO as a World Heritage Site, but unfortunately, you should know that it was a clamorous economic failure. After long preliminary works a sample house was built, which was to serve as a model for dozens of similar villas, all between 200 and 300 square meters and with a private garden. But there was not even a single buyer, and in the end the only people who moved there were the patron Güell, Gaudí himself (along with his sister), and his architectural studio.
FUN FACT: all parks have their own benches, but only Güell Park has a bench that's 150 meters long! But you'll also have to work hard to get there, and will enjoy the well-deserved break...