I don't know why you would expect to be IN ancient Rome. That is when/where Latin was spoken.
As for using English, it is "MAY I go to the bathroom" if you are asking for permission.
If, instead, you are inquiring as to whether or not you are physically ABLE to get yourself TO the bath room, then you say "CAN I got to the bathroom"
This must be a homework assignment. Sorry, but if you cannot do the work yourself, you don't deserve a passing grade.