My only lilac tree was planted about 20 years ago. It was one of my 'must have' trees after the dogwood and Japanese weeping cherry.
Lilac belongs in the olive family (Oleaceae), genus syringa, which derives from the word syrinx, meaning a hollow tube or pipe. There are about 20 - 25 species in this genus.
Syringa vulgaris is the state flower of New Hampshire, because it "is symbolic of that hardy character of the men and women of the Granite State," according to Wikipedia.
I somehow identify the lilac tree with "My Fair Lady" and the song "On the street where you live", especially the lines "Are there lilac trees in the heart of town?..." and "Let the time go by, I won't care if I can be on the street where you live".
Lilac has its own unique color and fragrance. I prefer the tree to the shrub, despite having to trim the tall branches every year. I kept mine a little taller than the roof top. It is another one of many May-blooming flowers.