The portrait is of the
Qian Long emperor, who reigned 1735-1796. It is his name,
Qian Long Huang Di ("The Qianlong Emperor").
I can't make out what the two characters beneath the (extremely stylized) building on the reverse are.
It won't be very old; probably not pre-2000. If I had to guess, I'd guess it was part of a set of medals commemorating each of the Qing Dynasty emperors. Such things are commonly seen for sale, both individually and in sets, in the souvenir stalls around historic sites in mainland China.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis