Mark Wahlberg Flaunts Big Muscles on 'Transformers 4' Set

Mark Wahlberg wears a tight gray t-shirt and shows off his big muscles while walking around the set of his new film Transformers 4 on Wednesday afternoon (August 28) in Chicago, Ill.

The 42-year-old actor was seen grabbing lunch with some crew members during a break from filming.

PHOTOS: Check out the latest pics of Mark Wahlberg

Mark‘s most recent film Pain & Gain, which also stars Dwayne Johnson, is now on Blu-ray and DVD so make sure to check it out if you missed it while it was in theaters!

10+ pictures inside of Mark Wahlberg on the set of his new film…