Quote Originally Posted by Saracen_Warrior
Castles were a good idea once they got good at architecture and masonry. All that became useless one cannons were invented though. Only for a short period of time were stationary posistions not stupid.
Castles maybe, but fortresses were almost impossible to take without heavy losses. This was because it was very resilent to gunfire and almost impossible to take by storm if the garrison was professional (and motivated) enough.

The siege of Rhodes (what, 1530s?) lasted 6 months, despite overwhelming odds between attackers and defenders. This was with cannons involved.
The Siege of Malta (1565) lasted 3 grueling months in the hot sun, costing tens of thousends of lives (mainly on the besiegers side). Fairly long if you consider the Ottomans (the besiegers) had a then-record amount of artillery aiming for the fortress walls on Malta.