HONG KONG — Three masked explorers appeared atop an apartment tower in Hong Kong’s North Point district and sent a black drone flying, over a clothesline, until it was buzzing more than 10 stories above the cars, trams and pedestrians on the street below.

If history was any guide, the explorers said, the building the drone was filming — a 1952 theater with unusual roof supports — would eventually be demolished because it is not on Hong Kong’s list of declared monuments.

The authorities are “renewing the city on behalf of the developers, not the people,” said one of the explorers, who goes by the alias Ghost in videos and whose pollution mask and fingerless gloves gave him the air of a bank robber or graffiti artist.

The explorers belong to HK Urbex, a so-called urban exploration collective whose expeditions often require trespassing or walks through dark, abandoned or dangerous sites. But unlike some urban explorers, they do not court danger purely for its own sake. Their primary goal is to peel back layers of history — sometimes literally, by digging through dust and trash — and forge a video archive of Hong Kong’s colonial-era environment.