Essay by Dr. Jeffrey Becker.

Hybrid in design

The Temple of Baalshamin in Palmyra was a first century C.E. sanctuary dedicated to one of the key gods of the city.* As with other Palmyrene architecture, the sanctuary of Baalshamin demonstrated hybridity of design—incorporating both Near Eastern and Graeco-Roman elements.
Temple of Baal Shamin, 1st century C.E. (Palmyra—in modern Syria) (photo: Verity Cridland, CC BY 2.0)
Temple of Baal Shamin, 1st century C.E. (Palmyra—in modern Syria) (photo: Verity Cridland, CC BY 2.0)

The cult

The temple’s cult is dedicated to Baalshamin or Ba'al Šamem, a northwest Semitic divinity. The name Baalshamin is applied to various divinities at different periods in time, but most often to Hadad, also known simply as Ba’al. Along with Bel, Baalshamin was one of the two main divinities of pre-Islamic Palmyra in Syria and was a sky god. The relief plaque below depicts a votive dedication by a worshipper—Baalshamin and Bel along with Yarhibol (the lord of spring with a solar nimbus) and Aglibol (a lunar divinity).
Limestone bas-relief dedicated by Ba’alay to Bel, Baalshamin, Yarhibol, and Aglibol. Limestone, dated January 121 CE., from Palmyra (Museum of Fine Arts, Lyon) (photo: Owen Cook, CC BY-SA 3.0)
Limestone bas-relief dedicated by Ba’alay to Bel, Baalshamin, Yarhibol, and Aglibol. Limestone, dated January 121 CE., from Palmyra (Museum of Fine Arts, Lyon) (photo: Owen Cook, CC BY-SA 3.0)

The architecture

The temple of Baalshamin was a prostyle (having free standing columns on the façade only), tetrastyle (four columns across the façade) temple of the Corinthian order with a deep porch (visible in the photo below).
A Corinthian capital includes several motifs, most obviously, the carved leaves of an acanthus plant. For more on the Greek orders see this essay and this video.
The temple was set within a colonnaded precinct (a colonnade is a row of columns). The temple building dated to c. 130 C.E. and represents an addition to a sanctuary that already existed by 17 C.E.
Temple of Baal Shamin, 1st century C.E. (Palmyra—in modern Syria) (photo: Juan Llanos, CC BY-ND 2.0), CC BY 2.0)
View of the porch with free-standing columns, and a pilaster visible on the flank, Temple of Baal Shamin, 1st century C.E. (Palmyra—in modern Syria) (photo: Juan Llanos, CC BY-ND 2.0), CC BY 2.0)
The temple itself is conventional in its external design, meaning it conforms to what one would expect from a Classical Graeco-Roman structure. The four freestanding columns across the facade are complemented by engaged pilasters at the sides and back.
A pilaster is a shallow, rectangular decorative feature projecting from a wall. A pilaster usually has a capital and a base, like a flattened, attached column. (source)
Temple of Baal Shamin, 1st century C.E. (Palmyra—in modern Syria) (photo: Juan Llanos, CC BY-ND 2.0), CC BY 2.0)
Temple of Baal Shamin, 1st century C.E. (Palmyra—in modern Syria) (photo: Paul Kidd, CC BY-NC-SA 2.0), CC BY 2.0)
The colonnaded precinct experienced several phases of development during the first century C.E. (prior to the addition of the current temple). By the time of the temple’s construction, the colonnade had become a so-called Rhodian peristyle—meaning one flank was taller than the other three. The complex continued to develop across the course of the second century.
The temple itself adopts a Near Eastern motif of including a window in each of the cella’s flanks, a trait that is not Graeco-Roman but that finds comparison in contemporary temples in Lebanon. These windows reflect the belief that the divinity dwelled in the temple.

Context

The Temple of Baalshamin in Palmyra is a rough contemporary of the Temple of Bacchus in Baalbek (now in Lebanon). Although dissimilar in scale (the Temple of Bacchus is a monumental building), both show the contemporary propensity in Roman provincial architecture of using forecourts to frame sanctuaries, as well as showing the widespread use of the Corinthian order. This is one of a number of sanctuaries in the city that demonstrates the great wealth of the Palmyrenes. Palmyra and much of the Roman Near East was rich in cultural diversity, a diversity expressed in many ways, including by means of art and architecture.
*Note: The current (August 2015) political situation in Syria has endangered the archaeological site of Palmyra and there are reports of severe damage done to the Temple of Baalshamin.
Essay by Dr. Jeffrey Becker

Additional resources:
Palmyra, UNESCO (video)
Paul Collart, “Reconstruction Du Thalamos Du Temple De Baalshamîn a Palmyre,” Revue Archéologique, Nouvelle Série, Fasc. 2 (1970), pp. 323-327.
Klaus Schnädelbach, Topographia Palmyrena (Documents d'archéologie syrienne; 18) (Damascus, 2010).
A. M. Smith, II, Roman Palmyra: Identity, Community, and State Formation (New York: Oxford University Press, 2013).
J. Starcky and M. Gawlikowski, Palmyre (Paris: Librairie d'Amérique et d'Orient, 1985).
J. B. Ward-Perkins, Roman Imperial Architecture (Yale: Yale University Press, 1981).