Whenever there is digging beneath the ground in Los Angeles for any reason, suspicions should be raised. Digging by who? For what reason? If, say, the digging is a proposed improvement project by the city water and power department, which necessitates digging beneath one of the original historic roadways (Sunset Blvd.) through the Beverly Hills/Bel Air region, past the Playboy Mansion and near the Getty museum, should suspicion levels be multiplied? Publicly disclosed project details include replacing wiring, adding underground circuitry, transformer and utility substations. During the construction taking years, traffic and public access will be tightly controlled. Specifics of exactly who will be doing the work is not known, or if "specialists" and "assessment teams" will be brought in at certain points to replace the regular work crews. If I were the suspicious type and believed there is a nefarious underground hive of activity beneath Los Angeles, I would pay close attention to this project. That route runs through some of the oldest and wealthiest neighborhoods and homes, many of them unseen behind high fences and gates. During construction, someone using a drone (if possible) to observe would be awesome.

https://www.nbclosangeles.com/news/local/Los-Angeles-Traffic-Sunset-Boulevard-405-Freeway-LADWP-Construction-511774191.html

https://www.ladwpnews.com/media-advisory-ladwp-announces-year-long-power-upgrade-project-on-sunset-blvd-in-greater-bel-air-area/

https://www.ladwpnews.com/sunset-blvd-to-undergo-partial-closure-june-25-2019-to-summer-2020-for-major-ladwp-power-infrastructure-project/

http://www.ladwp.com/BelAir

https://virtualglobetrotting.com/map/hugh-hefners-home-playboy-mansion/view/google/

Frequent large scale digging operations throughout the Los Angeles region have been ongoing since it's founding days. For example:

https://www.wehoville.com/2014/09/20/sunset-la-cienega-developer-seeks-permission-alter-sunset-blvd-traffic-flow/