Nightly News | December 20, 2013
>>> there is something weird going on underground in one of america's big cities . underneath the streets of seattle something is standing in the way of progress, but what is it? nbc's joe fryer has our report.
>> reporter: in a city known for a giant needle that stretches toward space, everyone is now talking about a massive machine stuck beneath the ground.
>> the fact that so many people are focused on something under the streets is fascinating.
>> reporter: they call her bertha, measuring 57 feet in dimester she's boring a tunnel through seattle to replace an aging road along the waterfront. 1,000 feet into the 9,000 feet journey, bertha came to a grinding halt.
>> we are puzzled about what's preventing us from moving forward.
>> reporter: there is speculation about what stopped bertha from boring.
>> it could be jimmy hoffa , sasquatch.
>> ancient egyptians .
>> reporter: it brings us to the museum of history.
>> the answer might be in this very room.
>> reporter: historian lorraine mcconnachey takes us back to the roots in the mid 1800s .
>> where bertha is now was water.
>> reporter: today it's buried by layers of fill leaving some to worry if the roadblock comes from the past.
>> it could be a loek motive, a steam engine, a boiler. we really don't know what's under there.
>> reporter: the process is under way to figure out what is down there. but getting there won't be easy. in fact, it could take weeks to solve the problem. they are digging wells to reduce pressure around ber with that so it is safe for crews to explore. odds favor a natural blockage like a glacial boulder.
>> once we get down there, if it is a boulder we've got equipment, the tools to break it up manually.
>> reporter: for historians captivated by the mystery bertha's lesson might be that sometimes you have to look back bf moving forward. joe fryer, nbc news, seattle .