Cambridge Castle remained only a basic fortification until 1284 when Edward I decided to undertake major expansion works. Over the next 14 years the king spent at least £2,630 on rebuilding the castle in stone. Edward's castle was four-sided, with circular towers at each corner, guarded by a gatehouse and a barbican. A circular stone keep was built on the motte. The result was a "major fortress in the latest fashion", albeit never quite completed. Edward stayed at the castle for two nights in 1294.