Reddit, I've unearthed an impenetrable capsule buried about 5 feet deep while renovating a business. What have I found?

http://imgur.com/a/j2JvM ^^^PICS^^^ I found this today while I was drilling through some tile at a small business nearby. We noticed the tip of it and spent about 4 hours drilling away at the concrete it was buried in. It must weight about 60 pounds and is pretty damn solid, but there seems to be something inside of it (definitely something(s) solid). As you can see in the pics, there's also a small slot to drop things in. You can't see through it, because the crack is angled and was made so that you can't really see down. Oddly enough, we actually found a small iron safe weighing about 20 pounds next to it, but it was unlocked and nothing was in it. The capsule was probably originally painted blue (most probably). There is no other writing on the capsule as well as the bottom of the capsule (not pictured) is just a circular solid blue surface. People of Reddit, might any of you know what this is?

TL;DR: Found a solid capsule about 5 feet underground; weighs about 60 pounds; pictures show a small engraved star as well as a serial #: 343922.

UPDATE1: I'm surprised with that there weren't too many people accusing me of karma-whoring. I tried that once by posting a video, which was later reposted and received a thousand or so karma, compared to my first post which received 2.

Anyways, I've got this thing in a bag sitting in my car. An ordinary hacksaw didn't even scratch it, and a hammer didn't even dent it. Thanks for all the info, previous users and locksmiths, although I've tried spinning off the door to no avail (it seems like it's locked). I'm going to call a friend of mine tomorrow who's got a metal saw to open it for me for free, rather than paying $50 or so to have it opened by Henrique at Home Depot. I've also inserted a hangar to try to see what's inside, but I couldn't really feel much, only some minor resistance.

I will post the final update when it's opened! As for now, stay tuned and thanks for the laughs!

[UPDATE 2] 6/25/12 3:56pm: Alright gents, I won't be getting it cut for a while. I've got a guy who'll cut it for free, but after his wife finishes up some hospital stuff this Wednesday. I wish I could get it cut today or sooner, but it'll probably cost money and I might as well wait. Sorry about the delay, but I do promise, again, that I WILL update on the results with pictures! Thanks for the advice on cutting, too!

As for the capsule, it's been bagged within several garbage bags and is sitting in the trunk of my car. God damn thing dented the back of my car cause it rolled around.

[UPDATE 3] 6/28/12 1:05pm: Sorry that it's not opened yet, but it's still sitting in the trunk of my car. I've been out of reach with the guy who's promised to open it for me. Don't worry, I WILL update this.