The act of going places you're not supposed to go. "Urban exploration" acts as an umbrella phrase for other terms like infiltration, draining, buildering and other actions which take place in an urban setting.
Often the act of urban exploration is illegal, as trespassing is usually necessary. However, the majority of urban explorers do not intend to vandalize property. One of the cardinal rules of urban exploration is "Take only photographs, leave only footprints".
Also known as "urban adventure" and "ue".
"There's an abandoned factory. Are you up for some urban exploration?"
"I trespass on abandoned properties to take photographs of decaying buildings. I am an urban explorer."