“We know that her blood was part of that ground,” Martha Hale Farrell said of her sister Maile Rachel Hale, who was 26 when she attended a financial technology conference on the 106th floor of the World Trade Center’s North Tower.

When Ms. Farrell, 43, and her sister, Marilyce Hale Rattigan, visited the memorial eight years ago, they brought along leis, ballet slippers, a bag of M & Ms, a mini soccer ball and a jar of sand to leave in honor of Ms. Hale.

“The magnitude is striking,” Ms. Rattigan, 46, said, “but for us, it was always a personal loss.”

The sisters were delighted to later learn that some of those items were displayed in the museum. A friend of theirs who visited had burst into tears at the sight.

“These beautiful things that were left for our own personal closure are touching people that never met her,” said Ms. Farrell. “It humanizes her to have people understand the weight of the beauty that was lost that day.”

The most common tributes left around the plaza tend to be flowers, photos, flags, embroidered patches, stuffed animals, ribbons and prayer cards. Tape or rocks are often used to secure items on the slanted parapets that line the pools.

“There’s only one way to get the photo to stay and not blow in the wind — you tape it to a chopstick and stick it in the groove,” said Corey Gaudioso, 28, who has brought family pictures over the years for his sister, Candace Lee Williams , a 20-year-old college student who was aboard the plane that crashed into the North Tower.

“We don’t want her to just be a name among names,” he said.

Letters are folded and tucked into inscriptions. Some are general and appear to be quickly jotted down by a visitor inspired in the moment. Others are more intimate.