Catedral Metropolitana de São Sebastião do Rio de Janeiro
Cathedral of St. Sebastian of Rio de Janeiro
a Roman Catholic church built between 1964 - 79
modern style based on Mayan architectural style of pyramids
(from Wikipedia)

After a half-hour walk from the Cathedral (my speed, but would have been 5 minutes for our son!), the plan was to ride the Santa Teresa Streetcar, called Bonde, over cobblestone streets to its "end of the line" each way, for an excellent way to get an overview of Rio's  inner city, to see some of Rio's famous "street art/murals" & colonial architecture.  It was 3:30.  Shockingly to us & dozens of people after we got there, the guard said it was closed for the day!!!  VERY disappointing, especially since this historic tramway has run continuously since its opening in 1877 (except for a brief 2011–15 suspension), & that it is one of the oldest street railway lines in the world.  https://en.wikipedia.org/wiki/Santa_Teresa_Tram   

So in the end we decided to go back to the hotel (considering time to get/wait for an Uber & a half-hour ride).  Today's Ubers were $3 hotel to the Steps (30 min.); $3.40 to the Slave Market (5-10 min.); $7.20 to the Library (5-10 min.); $8 to the Cathedral after lunch (5-10 min.); & $6.40 back to the hotel (30 min.).  The reason I mention costs is to show the big differences . . . the time of day considering the possible amount of traffic & the number of Uber requests at that time; how close an Uber is to your pickup point; etc.  WHY it cost so much to go to the Library & the Cathedral . . . the distances being a stone's throw vs. the hotel-to-Steps miles, I have no idea . . . maybe because it's the high tourist area & people will just pay it, but for us it was fine because each of these rides was for 3 people because Uber charges for the distance, not the # of passengers.  And the speed & convenience was exceptional, all over, whenever we needed to go someplace.  In total it was $28 for 3 of us to get all around this day ~ each place from doorstep to doorstep ~ a good deal.

Sundown would now be in about an hour.  Our son had time to whip out to the beach for a stroll & photos, & then go to the local grocery store for breakfast items such as juice, cereal bars, yogurt, croissants, gallon jugs of water, a few sweets, etc., AND SURPISE of all surprises (as he said, an early Mother's Day gift🤗!), he found a Rio de Janeiro food tin filled with sugar cookies (yeah - a 40-year collection already ~ ~ ~ it will be in the Tins of Taste Museum in my on-going project of the NationalBreadMuseum.org)

The other important item was for our son to have time to find a guided tour for tomorrow's visit to the Statue & Sugar Loaf Mt. (using a cell phone to do internet research & booking).  It also gave me time to read tourist info about items in the city which would be of interest.  When we planned this Rio trip, originally one day was to be a 4-hour bus ride to a historic colonial city our son wanted to visit, and we'd get to see some countryside.  But with the forecast of rain Friday afternoon & Saturday, that had to be scrapped.  What happens is that if you have one chance, in your entire lifetime, to get to the top of the Statue & Sugar Loaf Mt., & they're covered in clouds (!!!) - - - well, you can figure it out, & that's exactly what happened by the time we got to the top of Sugar Loaf Mt. on late Friday morning.  There we had no cloud cover, as it was when we were at the Statue, but now we could no longer see Christ the Redeemer Statue as it was all cloud covered!  It was another reason for the time efficiency of being on a booked tour which had a vehicle & driver & began early.