Question: Il promo d'oro marked the wedding between Leopold I and what relation of Kind Philip IV?

Context articles: Monument to Philip IV of Spain
Baltasar de Zúñiga
Portrait of Philip IV in Armour
Philip IV of Spain
Philip IV in Brown and Silver
Il pomo d'oro
Equestrian Portrait of Philip IV
Margaret Theresa of Spain
Millones
Philip Prospero, Prince of Asturias

The Monument to Philip IV or Fountain of Philip IV is a memorial to Philip IV of Spain in the centre of Plaza de Oriente in Madrid, Spain.
 It was raised at the insistence of Isabella II of Spain in the first half of the 19th century, opening on 17 November 1843, a year before Narciso Pascual y Colomer came up with the square's final layout.
 However, its equestrian statue of the king dates to the 17th century and was produced by the Italian sculptor Pietro Tacca using scientific advice from Galileo Galilei and drawings by Diego Velázquez and a bust by Juan Martínez Montañés (who also collaborated on the work).
Baltasar de Zúñiga (1561 – October 1622) was a Spanish royal favourite of Philip III, his son Philip IV and a key minister in two Spanish governments.
 In control of foreign policy from 1618 to 1622, he was responsible for Spain's initially successful entry into the Thirty Years War (1618–48) and for the appointment of his nephew, the Count-Duke of Olivares to the position of prime minister for much of the reign of Philip IV.
 De Zúñiga was also notable as being one of the very few Spanish royal favourites of the period to die whilst still in favour.
The Portrait of Philip IV in Armour is a portrait of Philip IV of Spain by Velázquez now in the Museo del Prado in Madrid.
 It is one of the artist's most realistic portraits of Philip IV and was one of the first he produced after being made painter to the king in 1623.
 Its style corresponds to the artist's beginnings in Seville and shows its subject in a sculptural style like a portrait bust, with abrupt colour contrasts.
Philip IV of Spain (Spanish: "Felipe IV" ; 8 April 1605 – 17 September 1665) was King of Spain (as "Philip IV" in Castille and "Philip III" in Aragon) and Portugal as Philip III (Portuguese: "Filipe III" ).
 He ascended the thrones in 1621 and reigned in Spain until his death and in Portugal until 1640.
 Philip is remembered for his patronage of the arts, including such artists as Diego Velázquez, and his rule over Spain during the challenging period of the Thirty Years' War.
The Portrait of Philip IV or Philip IV in Brown and Silver is a portrait of Philip IV of Spain painted by Diego Velázquez.
 It is sometimes known as "Silver Philip" and is now in the National Gallery in London.
 It was the main portrait of Philip painted by Velázquez in the 1630s, used as the model for many workshop versions.
Il pomo d'oro ("The Golden Apple") is an opera in a prologue and five acts by the Italian composer Antonio Cesti with a libretto by Francesco Sbarra (1611-1668).
 It was first performed before the imperial court in a specially constructed open-air theatre Vienna in 1668.
 The work was so long it had to be staged over the course of two days: the Prologue, Acts One and Two were given on July 12; Acts Three, Four and Five on July 14.
 Originally planned to mark the wedding of the Habsburg Holy Roman Emperor Leopold I and Margaret Theresa of Spain in 1666, the production was rescheduled to mark the Empress's 17th birthday in 1668.
 The staging was unprecedented for its magnificence (and expense).
 The designer Ludovico Ottavio Burnacini provided no fewer than 24 sets and there were plenty of opportunities for spectacular stage machinery, including shipwrecks and collapsing towers.
The Equestrian Portrait of Philip IV was a portrait of Philip IV of Spain on horseback, painted by Velázquez in 1635-36 as part of a series of equestrian portraits for the Salón de Reinos at the palacio del Buen Retiro in Madrid (a series that also included that of Philip's son prince Balthasar Charles).
Margaret Theresa of Spain (Spanish: "Margarita Teresa" , German: "Margarete Theresia" ; 12 July 1651 – 12 March 1673) was, by marriage, Holy Roman Empress, German Queen, Archduchess of Austria and Queen of Hungary and Bohemia.
 Daughter of King Philip IV of Spain and elder full-sister of Charles II, the last of the Spanish Habsburgs, she is the central figure in the famous "Las Meninas" by Diego Velázquez, and subject of many of his later paintings.
The Millones were an indirect tax on food in Spain in the 16th and 17th centuries.
 They were first imposed by Philip II and were approved by the Cortes de Castilla 4 April 1590.
 The tax was initially intended in 1590 as a temporary measure to replace the Spanish Armada lost in attacking England.
 The "millones" was voted by the Cortes of Castille in 1590 as a 6-year grant for 8 million ducats.
 It was originally levied on the "cuatro especies" of wine, meat, olive oil, and vinegar.
 The tax was renewed by the Cortes in 1596, and used as well by Philip's successors Philip III, Philip IV and Charles II.
 Under Philip III the tax brought in 3 million ducats a year, although that fell back to 2 million ducats a year due to population loss and recession at the end of his reign.
 In 1626, Philip IV and his Cortes doubled the tax to the level of 4 million ducats by also levying it on salt, paper and ship anchorage in lieu of proposed taxes on offices, grants and property; in the Cortes of 1632, the tax raised an additional 2.5 million ducats a year because it was levied on chocolate, sugar, fish, tobacco and other commodities.
 From 1655, renewal of the tax was practically automatic, and from 1668 it was renewed by the "Junta de asistentes" that the king called together in lieu of bringing together the full Cortes.
Philip Prospero, Prince of Asturias (Felipe Próspero José Francisco Domingo Ignacio Antonio Buenaventura Diego Miguel Luis Alfonso Isidro Ramón Víctor; 28 November 1657 1 November 1661) was the first son of Philip IV of Spain and Mariana of Austria to survive infancy.
 Philip IV had no male heir since the death of Balthasar Charles, his son by his first wife, Elisabeth of France, eleven years before, and as Spain's strength continued to ebb the issue of succession had become a matter of fervent and anxious prayer.