Best to start with one of Gaudi's most famous works in Barcelona if interested to follow his traces all across town. The construction of this giant temple started in 1882 not expected to be completed for another 30 to 80 years.
Until his death in 1926, Gaudi played an active role in directing the construction while today new materials are being used which Gaudi himself may not have used, all noticable in the contrasts in the stone colour as well as the actual style of construction of the new and old parts of the building.
You will be stunned by the extensive decorative elements of the façades in bright colours as well as the main front of La Pasión decorated with a cryptogram- besides the door of El Nacimiento.Anyway, not yet familiar with Gaudi's work, this magnificent building is a good staring point and an absolute must-see if visiting Barcelona!!!