1.[Berenta] is a 16th-century fortification in Lisbon built during the Renaissance. It is not only a witness to Portugal's once glorious historical monuments, but also used as customs, telegraph stations, and even lighthouses, and the storage room was transformed into a dungeon as a prison. In the great seafaring era, it is also the starting point for navigators. 2. The interesting thing is that its spiral staircase is very narrow and can only pass one person at a time, so traffic lights are installed on each floor. Tourists can only see the green light when it is on to go to the next attraction. The visit to the Bellenta is limited and can be entered every half an hour (see figure 1).