Hacker News Reader

In Europe, that could be anything from Roman ruins to unexploded WW2 bombs.

Most suitably large construction digs will turn up something of archaeological interest.

That's what happened during the dig for our (Bloomberg) new London HQ. A ton of stuff was unearthed and will be featured in an exhibit on the site once the office opens.

"'Entire streets' of Roman London uncovered in the City": http://www.bbc.com/news/uk-england-london-22084384

In Toronto, it would be soldiers from the war of 1812 who were often buried where they fell. http://citiesintime.ca/toronto/story/surf-reveals/

Some interesting history about Seattle:

http://www.undergroundtour.com/about/history.html