[4Tran]

It really depends on what you're looking for (heck, I don't even think a show should be considered old unless it aired at least fifteen years ago), but there's plenty of older stuff that anime fans should check out:

Rose of the Versailles (1979) - a rarity in anime; it's a pure historical drama. And it's so well made that there isn't much out there that can compare favorably to it.

Oniisama E (1992) (aka Brother, Dear Brother) - this is the true precursor to shows like Maria-sama ga Miteru. It's also arguably the most melodramatic anime ever made.

Aim for the Ace is probably worth checking out as well - all three works were originally created by the same mangaka. Unfortunately, I have no idea where you'd be able to find a copy of it, and I haven't seen it yet.

Macross (1982) - originally planned as a parody of Mobile Suit Gundam. However it rather transcends the mecha genre by focusing more on personal stories featuring tons of great dialogue. Macross also has a very good feel for war and military affairs - making it one of the most realistic mecha shows around. In my opinion, the "Do You Remember Love" movie ranks as the second-most beautiful anime movie of all time.

Gunbuster (1986) - originally a parody of Aim for the Ace, but by its conclusion, it's one of the more touching mecha anime ever. As an added bonus, it has tons of great dramatic and action-packed moments. Gunbuster is possibly the best work of Anno Hideaki.

Nausicaa (1986) - all Ghibli films are good, but this is the movie that allowed them to form the company in the first place.