Which of the following was a common feature of Roman temples?

Large pillars, often found in Roman temples, served both structural and aesthetic purposes. These pillars, typically made of stone or brick and often adorned with elaborate capitals, formed colonnades that supported the temple's roof and created a grand, inviting entrance. This architectural style was heavily influenced by Greek designs, adapted to incorporate the distinct characteristics of Roman engineering and artistry. The presence of large pillars allowed for open and spacious interiors while also emphasizing the temple's verticality, thereby projecting a sense of power and divinity associated with the gods worshipped within these sacred spaces.

The other options, although they may represent aspects of Roman architecture or urban design, do not pertain directly to the essential features of Roman temples. Open-air theatres, decorative gardens, and subterranean chambers serve different purposes and were not typical elements incorporated into the structure or design of temples dedicated to the gods.