The most commom chemical used for dissoving gold should be Aqua regia (Royal water).
Aqua regia is a mixture of conc. nitric and conc. hydrochloric in ratio of 1:3, it got the name "royal water" because it can and it use for dissolving noble metal including Gold.
Aqua regia can dissolve gold because of oxidising properties of conc. nitric and the free chlorine produce by conc. hydrochloric .
You may find out more infomation about aqua regia by looking at wiki.
http://en.wikipedia.org/wiki/Royal_water
Also, some other superacid may dissolve gold, but it will not be discussed here.
About alkali, gold may dissolve in alkali cyanides (eg, sodium cyanides), thiocyanates ,double cyanides.
Gold may also dissolve by halogens, such as aqueous halogens, oxidizer containing halogens.