[4] He was likely recruited to work in Mantua in 1659, by his fellow Flemish painter and architect Daniel van den Dyck.

Van den Dyck had been appointed by duke Carlo II Gonzaga, Duke of Mantua as the prefetto delle fabbriche ('Prefect of the Buildings'), a position which combined the duties of official court painter, architect, surveyor of the Ducal construction program and engineer for theatrical stage design.

He also participated on a book containing the libretto by Francesco Sbarra for the opera Il pomo d'oro scored by Antonio Cesti, which was staged twice in July 1668 on the occasion of the marriage of Emperor Leopold I and Margaret Theresa of Spain.

The folio de luxe edition of the book holds a print designed and etched by Geffels showing the opera's performance with Emperor Leopold I and his bride in attendance.

The theatre in which the opera was staged had been purpose-built on the occasion of the couple's wedding after a design by Ludovico Ottavio Burnacini.

[1] Even after his return to Mantua later in 1668, Geffels maintained contact with the Viennese court, as evidenced by his collaboration on the three-volume book by Gualdo Priorato with the title Historia di Leopoldo Cesare and also by his paintings depicting the Relief of Vienna in 1683 (Wien Museum Karlsplatz) and the Retaking of Buda in 1686 (Hungarian National Museum).

[1] Geffens' official duties at the Mantua court included the design and execution of ephemeral objects and structures used on the occasion of important court-related events.

Frans Geffels was commissioned to design and construct a funeral monument that was set up in the middle of the church during the mass.

A print of the design was included in the book by Antonio Gobio and Geffels entitled Le essequie celebratesi nella chiesa delle MM.

[16] For the Relief of Vienna Geffels relied on a print engraved by Johann Jakob Hofmann after a design by Justus van den Nypoort published soon after the events happened.

The portrait shows the Duke at full length with a page on his side who is handing him a letter on a pewter plate.

[19][20][21] His Dinner Party on a Terrace, (Philadelphia Museum of Art, 1660s) was previously attributed to the Dutch painter Pieter de Hooch.

It shows some figures who may be Romani people possibly preparing a meal and a shepherd with a herd inside a tunnel-like grotto with Antique architectural elements.

The tunnel in the picture is likely not an existing Antique structure but was created by combining motifs from different locations, which Geffels may have known through print publications.

The work with its complex perspective of the tunnel grotto demonstrates how Geffels was able to put his skill as an architect and theatrical designer to good use in his paintings.

This series of seven plates includes a frontispiece with a dedication to Marchese Ottavio Gonzaga and six prints showing figures amidst classical ruins.

In his native Antwerp he must have familiarised himself with the home and workshop and annex courtyard garden that Peter Paul Rubens had designed for himself based on his artistic ideals.

Rubens had further published in 1622 the Palazzi di Genova, an important book illustrated by himself, which depicted and described the palaces of Genoa in Italy in 72 plates.

Further, working with Daniel van den Dyck during his early years in Mantua must have given him further opportunities to hone his skills as an architect.

[26] The first palace in Mantua for which Geffels made the designs was the Palazzo Gonzaga di Vescovato in Portiolo on which he worked in 1662.

It is composed of a single giant row of four pilasters with composite capitals framing a central doorway, a rectangular window on each side, and three niches with large shells surmounted by pediments.

[26] He reworked the façade of the inner courtyard, which included a statue of Jove and painted decorations combined with stucco reliefs.

[14] The Baroque façade extending over two floors shows a horizontal sequence of paired windows which contrasts with the vertical dynamic created by the balustrades on the belt course.

[14] Geffels designed an artificial natural environment, decorated with wells, stalactite caves, mythological sculptures for the palace.