I think that you have a Rome coin with a mint mark of RBS, similar to the coin I have attached below. The bust also looks more like Rome.
COMMAGENE, Zeugma. Philip I the Arab. 247-249 AD. Æ31, 19.2g; 6h (a nice chunky coin, how about that?) Obv.: AYTOK K M IOYΛI ФIΛIΠΠOC CЄB; Laureate, draped, and cuirassed bust right. Rev.: ZЄYGM-ATЄΩN; Peribolos containing grove of trees, seen in perspective; tetrastyle temple in distance, draped figure within (Zeus?); in exergue, capricorn to right. Reference: Butcher 31c; BMC 35.
The temple of Vesta in Rome. Julia Domna. Struck 214. 27-24 mm. as. 10.15 grams. IVLIA PIA FELIX AVG Julia sacrificing over altar, accompanied by three Vestal Virgins, temple of Vesta with four columns. Sear II 7137. "The temple had been restored by Julia Domna some years earlier." RIC 607.
Very nice example Warren, especially like the reverse as usually I only see worn examples unlike yours.
Antoninus Pius A.D. 150- 151 Æ Sestertius 30x31mm 27g IMP CAES T AEL HADR ANTONINVS AVG PIVS P P; laureate head right TR POT XIIII COS IIII S-C PIETAS; Octastyle temple, in which are seated Augustus and Livia. RIC III Rome 873 The reverse commemorates the restoration of the temple of Divus Augustus and Diva August (Livia) Julia Domna Ionia, Smyrna A.D. 198- 202 26mm 11.5gm ΙΟΥΛΙΑ CЄΒΑCΤΗ; draped bust right. Є CΤΡ Μ ΑΥΡ ΓЄΜΙΝΟΥ / CΜΥΡΝΑΙΩΝ, tetrastyle temple with cult statue of Tyche. BMC 387.8.32; Lindgren 397 Faustina I after A.D. 141 AR Denarius 17x18mm 3.1gm DIVA FAVSTINA; draped bust right. AED DIV FAVSTINAE; Hexastyle temple in which is seated figure of Faustina I. RIC III Rome 343 Philip I A.D. 248 AR Antoninianus 22x23mm 3.9g IMP PHILIPPVS AVG; radiate, draped and cuirassed bust right. SAECVLVM NOVVM; Hexastyle temple with statue (of Roma) in center of columns. RIC IV Rome 25b Celebrating the Secular Games for the 1000th year anniversary of the founding of Rome Gallienus A.D. 258-259 AR Antoninianus 21x22mm 3.8gm GALLIENVS P F AVG; Radiate and cuirassed bust right. DEO MARTI; Mars in temple. RIC Vi Lyons 10; Göbl 889h Cologne Attributed to Lyons in RIC, but more recently reattributed to Cologne in Göbl Maxentius A.D. 307 24x25mm 5.2g IMP C MAXENTIVS P F AVG, laureate head right. CONSERV VRB SVAE, Roma seated left on shield within tetrastyle temple, holding scepter and handing globe to Maxentius, standing right and holding scepter, with foot on bound captive seated right; Victories as acroteria, she-wolf and twins in pediment. In ex. AQΓ RIC VI Aquileia 113
The temple of Roma: Probus, 276-282 IMP PROBVS AVG, helmeted bust left with spear and shield. ROMAE AETERNAE, 6-column temple (of Roma) with Roma within holding Victory and long staff. R*Γ in exergue. Sear III.12027 RIC 195G I have a page on books and catalogs that emphasize architectural types: http://augustuscoins.com/ed/catalogs/architectural.html They make a great collecting theme.