There are two oddities in downtown Rio and they sit near each other. The first is the Catedal de Sao Sebastião do Rio de Janeiro. This tall cylindrical building does not look like any other cathedral in the world. It was built in 1960 and holds up to 20,000 people.  They are very proud that the catholic pope visited here once. The interior is actually very pretty because there are 4 major stain glass windows that stand 90 meters (316 feet) high. Nearby is an old aqueduct that was built around 1750 to carry water to the city. Now it carries a tourist trolley.