The Baths of Trajan Decius — or of Philip the Arab?

Why did Decius delay his departure for the frontier in the spring of 250? Aurelius Victor is clear on this point.

Romae aliquantum moratur, moenium gratia, quae instituit, dedicandorum.⁵⁴

[Decius] remained for some time at Rome in order to dedicate a public building which he built.⁵⁵

Because our sources document only one public building dedicated by Decius at Rome, it is virtually certain that Victor is referring to the imperial thermae on the Aventine.⁵⁶ La Follette asserts that Victor here “clearly refers to new construction begun by Decius.”⁵⁷ However, the text is not explicit on this point.

Is it possible that Decius planned, built, and dedicated an imperial bath complex in less than one year, between his arrival in Rome in the autumn of 249 and his departure in the summer of 250? The Baths of Caracalla were begun in 211 or early 212 and dedicated in 216, although the construction of the surrounding porticoes probably dragged on until the reign of Severus Alexander.⁵⁸ The Baths of Diocletian took between seven and eight years to complete, from 298 to 305 or 306.⁵⁹ To judge from the size of the rooms recorded by Palladio, Decius’ baths must have been significantly smaller than either of these--perhaps less than one-quarter the floor area of the gigantic Baths of Diocletian. Still, it is wrong to assume that construction time is simply a function of floor area. Architectural planning, site procurement and clearance, and the production and transport of building materials are subject to their own timetables, independent of the dimensions of the final product.

Of course, the most important factors affecting construction speed are the financial and manpower resources available for a given project. Though our evidence for imperial finances in the mid-3rd c. is incomplete, there is good reason to believe that Decius was short of cash throughout his reign. We can identify several extraordinary expenditures which must have drained the imperial treasury in the period before 250. First, there was the huge ransom, (reportedly 500,000 denarii) paid by Philip to the Persian Shahpuhr at the conclusion of the disastrous eastern expedition in 244.⁶⁰ Zosimus reports that Philip also gave an especially generous donativum to the troops to grease his way to the throne.⁶¹ This was followed by a congiarium of 350 denarii for each household on the dole in Rome.⁶² Next there was the celebration of the millennium of the Roman state which took place in 248. The lavish festivities surrounding this event, which featured the deaths of “innumerable” wild animals and three days and nights of theatrical presentations, must have been hugely expensive.⁶³ On Decius’ accession in 249 a hefty donative was surely demanded by the Danubian troops who raised him to power. Decius also distributed the customary largess to the plebs, but this was reduced, significantly, to only 250 denarii per household.⁶⁴

On top of all this we must take into account the costs of civil war. Philip had to deal with Jotapian in the East,⁶⁵ Marinus Pacatianus in Upper Moesia,⁶⁶ and finally Decius himself. Decius faced the revolts of Priscus in Thrace⁶⁷ and Julius Valens Licinianus.⁶⁸ Disastrously expensive to wage, the virtually continuous civil conflicts during the reigns of Philip and Decius also meant that tax revenues from the provinces occupied by usurpers were unavailable to the government in Rome. The income side of the imperial ledger was probably also affected by an agrarian crisis in Egypt, the result of the failure of the annual Nile flood.⁶⁹ The cumulative effect of all of these factors must have left the imperial treasury severely depleted during Decius’ brief reign.

In La Follette’s view, Decius’ baths need not have been finished at the time of dedication, in 250, since “the dedication of a building could occur at almost any time during its construction.”⁷⁰ She bases this opinion on the evidence of the Baths of Caracalla, which, according to the Historia Augusta, were dedicated before completion:

. . . et lavacrum quidem Antoninus Caracallus dedicaverunt et lavando et populum admittendo, sed porticus defuerant, quae postea ab hoc subditicio Antonino exstructae sunt, ab Alexandro perfectae.

. . . and in fact, Antoninus Caracalla dedicated the bath, and bathed in it and opened it to the public, but the portico was left unbuilt. This was added later by this counterfeit Antoninus [Elagabalus], and finished by Alexander.⁷¹

It is clear from this passage that the central block of Caracalla’s baths must have been substantially complete when the emperor dedicated it, opened it to the public, and . We cannot take this as evidence that dedication ceremonies were regularly performed over half-finished construction sites.

La Follette suggests that part of the impetus behind the bath project was Decius’ desire to emulate his great predecessor and namesake, Trajan.⁷² Certainly, an astute politician like Decius would not have been blind to the propaganda value of new public building in the capital. But Decius had other priorities: his campaign of religious revival, his transportation infrastructure program, and the defense of the empire against threats from usurpers and barbarians. The absence of evidence for other public construction projects during Decius’ principate suggests that building was not high on his list of priorities. To summarize, Decius had neither the time, nor the resources, nor the inclination to begin a major public building project in Rome. However, if he had inherited a bath complex that was partly or nearly complete, it would have been natural for him to finish it and take credit.