Former New York City Mayor Ed Koch died this morning after being admitted to the hospital earlier this week. He was 88.

Twitter users shared memories of the colorful three-term mayor.

As prayers and remembrances come in, many struggle to imagine a New York City without Ed Koch.

RIP, Mr. Mayor.

NYC has lost an irrepressible icon and our most charismatic cheerleader. Ed Koch was a great mayor, a great man, and a great friend.

Koch’s last tweet before he was hospitalized:

Editor’s note: Additional tweets have been added since this post was first published.