antiguamente, adverb:

once, formerly; in the old days

Antiguamente, the adverb from antiguo, has two different shades of meaning. On the one hand it can just refer to something which used to happen formerly, picking up on the meaning of former in antiguo:

un barrio donde antiguamente se alojaba una base militar
militar an area where there used to be a military base

On the other hand, antiguamente refers to the dim and distant past, in the old days.

Antiguamente era costumbre de los enamorados llevar al cuello algo que les recordara* al amante.
In the old days people in love used to wear something round their neck to remind them of their loved one.

Sometimes the two meanings coalesce:

como se decía antiguamente
as people used to say (in the good old days)