In order to conserve the limited bandwidth available, ISO images are not downloadable from mirror.centos.org

The following mirrors should have the ISO images available:

http://mirror.umd.edu/centos/7.8.2003/isos/x86_64/
http://mirror.chpc.utah.edu/pub/centos/7.8.2003/isos/x86_64/
http://mirrors.oit.uci.edu/centos/7.8.2003/isos/x86_64/
http://mirror.nodesdirect.com/centos/7.8.2003/isos/x86_64/
http://mirrors.tripadvisor.com/centos/7.8.2003/isos/x86_64/
http://mirror.cc.columbia.edu/pub/linux/centos/7.8.2003/isos/x86_64/
http://mirror.arizona.edu/centos/7.8.2003/isos/x86_64/
http://mirror.hostduplex.com/centos/7.8.2003/isos/x86_64/
http://yum.tamu.edu/centos/7.8.2003/isos/x86_64/
http://mirror.netdepot.com/centos/7.8.2003/isos/x86_64/
http://ftp.usf.edu/pub/centos/7.8.2003/isos/x86_64/
http://centos.mirror.ndchost.com/7.8.2003/isos/x86_64/
http://atl.mirrors.clouvider.net/CentOS/7.8.2003/isos/x86_64/
http://centos.mirror.constant.com/7.8.2003/isos/x86_64/
http://mirror.trouble-free.net/centos/7.8.2003/isos/x86_64/
http://mirrors.ocf.berkeley.edu/centos/7.8.2003/isos/x86_64/
http://centos-distro.1gservers.com/7.8.2003/isos/x86_64/
http://ftp.ussg.iu.edu/linux/centos/7.8.2003/isos/x86_64/
http://mirror.ash.fastserv.com/centos/7.8.2003/isos/x86_64/
http://mirror.sesp.northwestern.edu/centos/7.8.2003/isos/x86_64/
http://packages.oit.ncsu.edu/centos/7.8.2003/isos/x86_64/
http://mirrors.unifiedlayer.com/centos/7.8.2003/isos/x86_64/
http://mirror.cogentco.com/pub/linux/centos/7.8.2003/isos/x86_64/
http://mirrors.lug.mtu.edu/centos/7.8.2003/isos/x86_64/
http://mirror.metrocast.net/centos/7.8.2003/isos/x86_64/
http://repo.ialab.dsu.edu/centos/7.8.2003/isos/x86_64/
http://mirrors.gigenet.com/centos/7.8.2003/isos/x86_64/
http://mirror.centos.iad1.serverforge.org/7.8.2003/isos/x86_64/
http://mirror.cs.pitt.edu/centos/7.8.2003/isos/x86_64/
http://mirror.team-cymru.com/CentOS/7.8.2003/isos/x86_64/
+ others, see the full list of mirrors: https://www.centos.org/download/mirrors/

Mirrors verified Wed Nov 11 18:10:32 2020 UTC

You can also download the ISO images using bittorrent, a peer-to-peer file sharing protocol. The .torrent files can be found from CentOS mirrors. Various bittorrent clients are available, including (in no particular order of preference): utorrent, vuze (Azureus), BitTorrent, Deluge, ctorrent, ktorrent, rtorrent and transmission. Packaged copies of various torrent clients for CentOS can be found in the repositories listed in the following wiki article: https://wiki.centos.org/AdditionalResources/Repositories