The best way to start to learn current value is to find the amount of recent (ideally within three months, no more than six) sales of comparable homes (type and floor space - within 10% -  being the two most critical factors) located within a 1-mile radius and in the same town.  It's called a CMA (Comparative Market Analysis) and any local Realtor should be able to generate one for you in about 20 minutes.  

That will show you the average and median price of comparable sold homes.  Multiply the $/SqFt by the SqFT of your subject home and you will have a good starting point for arriving at a current value.  

From there you can adjust up or down for anything you know about the home, or comparable sold homes.  For an outrageous example, if the home has had a recent fire, the value would be substantially less; if after the fire it had been completely redone to current standards it would be worth substantially more.  Most price adjustments are a lot more subtle than that, but you get the idea.  

The only way to get a more accurate value is to hire a professional appraiser (typically somewhere around $400 depending on the size of the home) assuming that you can give the appraiser interior access.  

It should all start with a call to a local Realtor. If it's any where in the greater Portland area, I'd be happy to help you with a CMA.