From 1904 until just a few years ago, the Monticello Street tunnel was one of the main routes in and out of downtown Somerset.
But now it has become a major eyesore.
“Just to be honest with you, I wouldn't want to walk through there. Because you never know what might be on the other side,” says Somerset resident Marie Ridner, who lives near the tunnel.
And it's not just spray painted slogans, drawings, and other things too vulgar to show. Trash, even old socks, line the pathway that many hoped after the new road was built would become a nice walkway.
“But I'd like to know when are they doing it? That's what I want to know. That's what I can't understand," said Ridner.
Police say they aim to find the vandals, prosecute them, and push for still penalties.
“We have stepped up patrols in this area. It our intention to catch those responsible,” said Somerset Police Det. Shannon Smith.
Cleaning the graffiti may not be possible, so police say they will probably have to paint over it.