The limit has been 1MB since a limit was created.
This isn't pedantically correct. It was actually lowered to 1MB by satoshi. I'll leave the code history spelunking as an excercise to the reader.
But correct, there was never a 256k limit. There is a 1MB limit. Also, for the longest time there was a 500k default target (half the limit), which was lowered to the typical block size when the target was made configurable.