My son did the same thing. It's time for a bed. And be prepared for him to not want to sleep alone. You'll have to find ways to work with him to get him to sleep in his own bed, in his own room.
After we read and tell stories, we stay with our son (lay down with him in the bed) until he falls asleep and then we leave him.
If you have security concerns, you can do what we did at first and put a gate on his door. That way you'll know he will stay in his room and yell for you when needed. But be sure there are no stools, chairs, etc. for him to use to climb over the gate. We don't use the gate on our son's door anymore (he's now 3), but we still use the gate at the top of the stairs so he can't wander around downstairs on his own, or get out of the house. (which I heard stories from friends about)
Good luck