Olympic Park in the Barra section of Rio de Janeiro opened for events yesterday and was full of activity through midnight, when the first of the swimming finals on the program concluded. (But if you were so inclined, you could see still events at that hour local time as across the city in Copacabana, Americans Kerri Walsh and April Ross began their competition at the beach volleyball venue with a midnight start time.) There was plenty of buzz though in the Olympic Park, where the U.S. men’s basketball team drew a huge and raucous crowd at Carioca Arena 1 and Venus Williams played on the tennis stadium’s center court. (The men’s basketball team had an easy time with China, Williams lost a three-set match.)

The Olympic Aquatic Stadium also made its debut and one of the things that immediately sticks out are the four enormous columns in each corner. There is a section of seating behind each of them, but it did not appear organizers were actually selling those seats, whose views are seriously obstructed. Other sight lines were also compromised in sections of the corners by thick railings.

Inside the park, lines for concessions were long but the atmosphere was light. Olympic rings are seemingly everywhere for people to take photos and the park’s huge merchandise store was open late and moving traffic through.

Here is a look at a few scenes from a memorable first night.