Old house with 2 prong outlets. is the box grounded?

Im renting a house for a steal of a price,(hence im not moving out) its a 3 bedroom 2 bath. problem is.. i think it was built in the 50's so every outlet in the house only has 2 prongs. I have read some posts on the internet and one said that the box may be grounded. could this be true, and can i test it myself? (i know how to turn off the circuit breaker and replace outlets) can i replace these outlets without an entire electrical renovation... ironically the guy who owned it before me was a career electrician. Should the whole house be grounded for resale in the future if it is not?