Palazzo Rospigliosi was initially built by Cardinal Scipione Borghese, nephew of Pope Paul V, as a summer residence near that of his uncle at Palazzo del Quirinale. The palace stands above the ruins of Terme di Costantino, the baths built by Emperor Constantine in 315 AD.
The view is taken from the green dot in the small 1748 map here below. In the description below the plate Vasi made reference to: 1) Ancient statue of a Roman Consul (now removed); 2) Secret Garden; 3) Palazzo della Consulta; 4) Walls around the courtyard; 5) Stables. 3) is shown in another page. The dotted line in the small map delineates the border between Rione Trevi (left) and Rione Monti (right).

Today

The view in December 2009
The view is very much as it was in the XVIIIth century, the only evident change being the garden which has replaced the cavallerizza, the horse training ground which you can see in the image used as background for this page.
The palace is now known as Palazzo Pallavicini Rospigliosi and it belongs to the Pallavicini who still reside in a part of it, while the rest of the building is occupied by tenants. The loggia is perhaps that which enjoys the most comprehensive view of Rome (for a page on Roman loggias click here).

Palazzo Rospigliosi

(left) Today's main gate; (centre) heraldic symbols of Cardinal Scipione Borghese; (right-above) heraldic symbols of the Altemps (ram) and of the Rospigliosi (diamond); (right-below) combined coat of arms of Rospigliosi (left) and Pallavicini (right)
The heraldic symbols which can be detected by walking around the outside of the palace offer a clue to its history. Cardinal Scipione Borghese started its construction soon after the election of his uncle (1605) and the architects involved in the design of the building and of the gardens were Flaminio Ponzio and Giovanni Vasanzio, the same architects who worked for the cardinal at Villa Borghese and at the restoration of Basilica di S. Sebastiano. Flaminio Ponzio was also involved in the design of Palazzo Borghese.
In 1616 Cardinal Borghese came to the conclusion that maybe he did not need this villa and sold it to Giovanni Angelo Altemps (in 1613 Altemps had sold Villa Mondragone near Frascati to the cardinal). Giovanni Angelo Altemps was the son of Roberto Altemps and he kept the property for just three years before selling it; after other changes of ownership in 1641 the palace was bought by Cardinal Giulio Mazzarino (Jules Mazarin) who left it to his heirs.
Eventually in 1704 the property which had lost its initial villa aspect to become more similar to an urban palace was acquired by Giovanni Battista Rospigliosi (nephew of Pope Clement IX) and his wife Maria Camilla Pallavicini; due to a complex testamentary trust the two sons of the couple started two separate branches of Rospigliosi and Pallavicini and they divided between them a large collection of paintings; the Rospigliosi experienced financial difficulties in the 1920s and sold their share of the property and collection. The Pallavicini still retain their gallery of paintings in the apartments where they live.

Casino dell'Aurora (Dawn)
The only work of art of Palazzo Rospigliosi which is accessible to the public (on the first day of the month only) is a painting (you can see it in an external link) by Guido Reni which gives the name to Casino dell'Aurora, a small building of the time of Cardinal Borghese. The painting was very highly praised and the subject was picked up again in 1621 by il Guercino in the decoration of the small casino of Villa Ludovisi, which is also called Casino dell'Aurora (you can see this other painting in an external link).

(left) Former main gate behind Palazzo della Consulta; (right) "Scala della Pastorella", winding staircase in Casino dell'Aurora
The main entrance to Palazzo Pallavicini Rospigliosi was penalized by the construction of Palazzo della Consulta in 1732-37; for this reason a small door on the wall along the street leading to Palazzo del Quirinale was turned into the main access to the palace; the old gate can still be seen behind Palazzo della Consulta.

The Secret Garden

The Secret garden known as "Il Teatro"

With wealthy enough looks and as bold as brass a visitor can tell the security guards that he has urgent business matters to discuss with one of the lawyers or institutions who have their offices in Palazzo Rospigliosi and then head towards the secret garden mentioned in the plate.

"Il Teatro": River Po

The garden belongs to the time of Cardinal Borghese and it was designed by Giovanni Vasanzio; the statues of the rivers are by Francesco Landini; they are a reminder of two gigantic statues of rivers which embellished the baths of Constantine and which were relocated in Piazza del Campidoglio.

"Il Teatro": River Tevere
Excerpts from Giuseppe Vasi 1761 Itinerary related to this page:

Palazzo Rospigliosi Fu questo principiato dal Card. Scipione Barberini con disegno di Flaminio Ponzio; dipoi fu proseguito dal Card. Giulio Mazzarini, e sotto altri poi terminato, oggi lo possiedono i Principi Rospigliosi. Occupa questo parte delle terme di Costantino Magno, e quivi furono ritrovate le maravigliose statue con li cavalli, che ora sono nella vicina piazza, e le due statue del pio Imperatore, una che sta sulla piazza di Campidoglio, e l'altra nel nuovo portico di s. Gio: Laterano, rozzamente fatte in quei tempi, in cui erano molto decadute le belle arti. Si vedono in questo palazzo de' quadri superbi, fra' quali nell'appartamento principale sonovi li dodici ss. Apostoli del Rubens, il fanciullo Gesù dall'Albani, il Sansone del Domenichino, il Baccanale del Pussino, ed altri del Caracci, di Guido, del Lanfranco, del Cortona, e del Maratti.

Next plate in Book 4: Palazzo Colonna
Next step in Day 3 itinerary: S. Silvestro a Monte Cavallo
Next step in your tour of Rione Monti: Palazzo della Consulta