I don't know how many popular tourism objects in Spain's Cadiz there are, but the Cathedral of Cadiz and it's bell tower should be among them for sure.
We visited Cadiz for couple of hours in June 2016, arrived here from El Puerto de Santa Maria by the ferry in the morning and left afternoon. There is a small entrance fee - EUR 5, which gives access both to the Bell tower and access to the church, audio guides are available as well. There is no lift to get up to the bell tower. The total height of bell tower is about 40 meters.
Cathedral of Cadiz
Tried to apply the panoramic photography above. Not the best result, but somehow framed (fit) whole building in one frame.
Cádiz Cathedral is a Roman Catholic church in Cádiz, southern Spain, and the seat of the Diocese of Cadiz y Ceuta. It was built between 1722 and 1838. The cathedral was declared Bien de Interés Cultural in 1931.
Climbing up the ramp
I was the only one visiting bell tower at this time (thus I met some German couple climbing down from the tower). The total height of bell tower is about 40 meters (131ft)
Levante Tower, one of the towers of Cádiz Cathedral, is open to the public and shows panoramas of the city from on high.
View from the Cadiz Cathedral tower
View towards bay of Cadiz
The Bottom Line:
Probably the best sights of Cadiz just for EUR 5.