You are welcome to just walk in and watch a wedding. We chanced to watch one 2 weeks ago in Madrid in San Jerónimo el Real, right next to the Prado. Man, the French did a lot of destruction in Spain during the Napoleonic era.
Quite formal wedding, ladies dressed to the nines. There is no bridal party, just dressed up kids as bride assistants. Pic is awaiting arrival of the bride. The party after at the Ritz was wild and crazy and went on until the wee hours.