July 31 is a very important day in Boston Celtics history, as the C's acquired Kevin Garnett in a trade on that date in 2007, completing their "Big 3" of him, Ray Allen and Paul Pierce. That group went onto win the NBA title in 2007-08 after a banner 66-16 regular season.

Here's what you need to know as you remember that era:

A 19-year veteran, Pierce spent 15 years with the Celtics, also serving as a key part of that championship group. In total, he was a 10-time All-Star, a four-time All-NBA selection, and the NBA Finals MVP in 2007-08.

He averaged 19.7 ppg for his career while also shooting 44.5 percent from the floor and 36.8 percent from three-point range.

Drafted No. 10 overall in the 1998 NBA Draft out of Kansas, he was inducted into the Basketball Hall of Fame in 2021.

In addition to Boston, he played for the Brooklyn Nets, Washington Wizards and Los Angeles Clippers.

A 21-year veteran, Garnett spent six years with the Celtics. In total, he was a 15-time All-Star, a four-time rebounding champion, a nine-time All-NBA selection and a 12-time All-Defensive team member. He won the league MVP in 2003-04 with Minnesota and was named the Defensive Player of the Year in 2008 with the Celtics, in addition to winning the title.

The Celtics acquired him on July 31 from Minnesota for Ryan Gomes, Theo Ratliff, Sebastian Telfair, Gerald Green, Al Jefferson, and two future first-round picks.

He stayed with Boston for those six seasons before getting dealt with Pierce, Jason Terry, DJ White, a first and second-round pick to Brooklyn for Keith Bogans, MarShon Brooks, Kris Humphries, Gerald Wallace and four future first-round picks.

One of those picks turned into Jaylen Brown, while another eventually turned into Jayson Tatum. That duo helped the Celtics win a title in 2023-24.

An 18-year veteran of the Milwaukee Bucks, Seattle SuperSonics, Celtics, and Miami Heat, Allen is one of the best shooters in NBA history. He was a 10-time All-Star, a two-time NBA champion and a two-time All-NBA selection. He was inducted to the Hall of Fame in 2018.

With Boston, he spent five seasons, averaging 16.7 ppg.

The Celtics acquired him a month before Garnett, bringing him in on June 28, 2007. He was acquired from Seattle with Glen Davis for Jeff Green, Wally Szcerbiak, Delonte West, Jeff Green and a second round pick.