Although his interests had a firm hold in genre themes – depiction of the daily life he observed around him in Copenhagen's streets, especially middle-class society – he would soon reach for the pinnacle of academic acceptability: the history painting.

It was therefore something to strive for, in spite of Marstrand's equal skill at depicting more modest themes, and of the enjoyment he had in portraying the crowds, the diversions of the city, and the humor and story behind the hustle and bustle.

At the same time Christian Waagepetersen, wine merchant to the Danish court and supporter of the arts, also became an important patron for Marstrand during this early period.

Marstrand's attempts at winning the medal were unsuccessful both in 1833 with his neoclassical "Flight to Egypt" (Flugten til Ægypten) and in 1835 with "Odysseus and Nausikaa".

He returned to Italy several times, the last visit being in 1869, and when in Rome he spent summer months each year in the hill towns Olevano Romano, Civitella and Subiaco.

Marstrand continued to travel regularly around Europe throughout his life, to (London, Vienna, Belgium, but especially to Italy and Rome), at times in the company of such fellow artists such as P. C. Skovgaard and Johan Adolph Kittendorff, or of art historian and critic Niels Lauritz Høyen.

He now supplied it with themes from literature and the theatre, portraying scenes from Don Quixote by Cervantes, as well as from Erasmus Montanus, or other plays by Ludvig Holberg.

Marstrand returned to portrait painting with even more seriousness in the late 1850s, depicting some of the key figures of the age, including Constantin Hansen (1852, 1862), Bernhard Severin Ingemann (1860), Grundtvig (1863), Høyen (1869), the architect Michael Gottlieb Bindesbøll, not forgetting his earlier portraiture of Købke in 1839.

He painted two remarkable great murals for King Christian IV's chapel in Roskilde Cathedral in 1864–1866, both of which have contributed to this popular monarch's enduring fame.

A series of paintings made during the last 6 years of his life featured a naked woman, while others were deeply religious, more inwardly so than the monumental work.

More relevant today is the rather striking number of his works which are now familiar signposts of Danish history and culture: scenes from drawing-rooms and streets of Copenhagen during his younger days; the festivity and public life captured in Rome; the many representative portraits of citizens and innovators; even the monumentalist commissions for university and monarchy.