Chotis are danced, calamari bocadillos and rosquillas are chomped and wine is consumed by the bota.
The heart of the festival is in Madrid’s La Latina district where a statue of the saint is taken from the San Isidro church for a parade around the streets.
Adults and children alike dress up the traditional chulapo/ chulapa outfits for the occasion – an outfit dating from the 19th century and adorned with red carnations.
Men don the traditional palpusa, a sort of black gingham flat cap.
All this is done to honour San Isidro, the humble labourer and miracle worker who brought forth a spring of holy water while ploughing the fields in the area now known as Provera de San Isidro, in the Carabanchel neighbourhood.
Tens of thousands of people gather there to picnic on San Isidro in a tradition that dates as far back as the 1600s.
The night ends with concerts on stages specially set up in Plaza Mayor, Las Vistillas or Provera de San Isidro and fireworks, this year set to music in the Parque Enrique Tierno Galvan.
Photographer Deirdre Carney shares her favourite photos taken around Plaza Mayor and La Latina during the festival.