The use of light inside the building for me was the most powerful aspect of the building. The colours streaming through the stained glass windows is captured by architectural shapes, not lost to the open spaces. Higher up the windows were designed by Gaudí to remain clear to allow as much natural light to fill the cavernous space, symbolising purity. The stained glass is still being fitted, designed by Joan Vila-Grau since 1999. On the day we visited a section of blue glass pieces were being fitted.
Columns are built using a wide range of geometric shapes,(ellipsoids, hyperbolic paraboloids, helicoids and conoids) inspired by nature rising to tree like branches to the roof.
Glory facade appears to have been recently started looking like a construction site of concrete and steel reinforcing. It was Gaudì's plan that this be the formal entrance to the church.
The Passion Facade is based on drawings left by Gaudí showing the twelve Stages of Cross of Jesus's death as depicted in sculptures by Josep Maria Subirachs.
The scenes on the Nativity Facade tell the "Christmas Story" of the birth of Jesus including the Three wise men and trumpet blowing angels.
From the look of the stage of construction there are still many years ahead before completion.
Tip: Do book online before you go. The line queuing for tickets wound around the corner. You do not need to print out your ticket confirmation, a problem when travelling, just take the credit card you booked with to the counter on the reserved tickets line and they will give you your ticket. The audio guide was worth getting. Book that at the same time.