An albarrana tower is a really big tower that people built a long, long time ago to help protect their cities from enemies who might want to come and attack them. It has a special shape that can make it harder for enemies to get inside the city.
It is called an albarrana tower because it is built separate from the city's walls. Think of it like a little castle all on its own that is connected to the bigger castle by a little bridge.
The people who wanted to protect their city would climb up to the top of the tower and they could see really far away. They could look out for enemies and warn the city if someone was coming. The tower was also really strong and hard to break through, with really thick walls that made it difficult for enemies to climb up and get inside.
Overall, the albarrana tower was a really smart way to protect people from danger and make sure everyone felt safe inside their city.