Rosamund would have presumably spent some amount of time in Sirmium (now Sremska Mitrovika, Serbia), which was under Gepid control in the mid-6th century. This city on the banks of the Sava was once the capital of the Roman province of Pannonia Inferior and, in the 3rd-century, served as a capital of the empire. It boasted forums, basilicas, enormous baths, an aqueduct, a hippodrome, an imperial palace complex, a fortified circuit wall, an extramural necropolis, and numerous urban villas, to say nothing of its more workaday businesses, marketplaces, and habitations. In its heyday, it would have looked something like this…

There aren’t many novels set in this part of the world in the 5th and 6th centuries (at least in English), but those that I’ve been able to find seem to treat Sirmium as a bastion of Roman society, its glory tarnished by the travails of history but still largely intact. My research suggests this was far from the case.