Fundraisers have one week to register for a charity run up the Beetham Tower in Manchester.
The Cystic Fibrosis Trust and Royal Manchester Children's Hospital Charity are looking for fundraisers to climb the 798 steps to reach Level 46 of the tower.
The Beetham Tower is the tallest building in the UK outside of London.
The Royal Manchester Children's Hospital Charity is raising money to ensure continued excellence in treatment, care and research at the hospital.
The Cystic Fibrosis Trust funds research to treat and improve the lives of people living with cystic fibrosis and aims to ensure appropriate clinical care, advocacy and support.
Soosie Rhodes, senior events manager at the Cystic Fibrosis Trust, said: "This vertical challenge invites people to run or walk up this iconic building with us. The goal is for everyone to finish by ascending at their own pace, then receive their commemorative T-shirt and medal."
All proceeds from the Beetham Tower Run will be split equally between the two charities.
About 120 participants have registered for the event so far but there are still a few places left.
Hannah Thomas, events manager at Royal Manchester Children's Hospital Charity, said: "We are delighted to be working with the Cystic Fibrosis Trust on the Beetham Tower Run. I would ask anyone looking for a last minute challenge to sign up and help us to make a real difference to people with cystic fibrosis and children being treated in our hospital."
Registration costs £15 and participants are asked to raise sponsorship of £100. To register visit the events section at www.cftrust.org.uk.