Authorities have declared the iconic Matterhorn mountain, on the Swiss-Italian border, off-limits for a day on the 150th anniversary of the first ascent to honor more than 500 climbers who have died trying to reach the top.

A group of seven mountaineers led by Briton Edward Whymper became the first to reach the top on July 14, 1865. Four members of the team died on the descent.

Swiss ceremonies commemorating the anniversary Tuesday included the re-opening of the Hoernlihuette base camp refuge.

Authorities have reduced the number of beds there to 140 from 170 in an effort to calm the crush of mountaineers trying to reach the 4,478-meter (14,692-foot) Alpine peak.