SAN DIEGO (NEWS 8) – City crews are digging for answers after uncovering tunnels beneath a San Diego landmark.

City of San Diego Public works crews unearthed the discovery near Balboa Park at Upas Street and Park Boulevard as they dug up the sidewalk to do electrical work on a pipeline.

It’s a trip indeed down memory lane for those who recall San Diego’s four underground tunnels that were safe passageways to nearby schools.

News 8’s TV Business Manager, Moana Pitcher, personally used the tunnel as a student as she walked to Roosevelt Middle School in the 1960’s.

“If you were going to get to the other side of Park Boulevard, you were going to go underneath, you know, through the tunnel,” said Pitcher.

It’s been 40 years since the underground passageway closed.

“It was a safe way to get across the street and you would either be with a friend -- it was dark -- or if it was a hot day, it would be really cool,” she said.

The tunnel was built in the 1930’s, along with three other school crossing tunnels to tackle traffic hazards.

The steps into the tunnel have since been covered by dirt, and graffiti decorates the walls.

Two years ago, News 8 with the El Cajon Boulevard Business Improvement Association crawled down over dirt in a 50-feet-long, seven-feet-tall tunnel under El Cajon Boulevard.

A map laid out the elaborate underground undertaking.

The newly discovered tunnel was shut down in the 1970’s, and will soon be sealed off.

“I am excited to know that it did get opened up, even if it’s not for keeps. It got opened up and it’s really there still for people to see,” said Pitcher.

Due to safety concerns, the public will not be allowed in.

The Upas Street pipeline work is expected to be completed late next week and the tunnel will be again closed for good.