There are quite a few entrances to the operation near Groom Lake, but these are the ones accessible by the public. Gate 700 on the Nevada Test Site also leads to Area 51, though you need permission from the Nevada Test Site to get there. Gate 700 can be seen on the NTS tour when you view the Sedan Crater. There are other border points of interest, such as Bald Mountain, that are only used by security.
