Addressing wedding invitations to Apartments, Condos, etc.

I am a calligrapher and am addressing the invitations for a friend’s wedding. I actually haven’t done any wedding invites for about 4 years now and it seems some of the ettiquette rules have changed since I learned them originally. What I would like to know is the proper way to address the invitation if the person lives in an apartment or condo, etc? Do you spell out Apartment and put on the second line? What do you use if it is not an apartment but a townhouse or condo? Is Unit acceptable?

Rebecca Black, Etiquette By Rebecca

Dear Addressing,

You would spell out appartment and write it on the second line. Unit would be fine, but many times the condo or townhome has its own address.

Best wishes,