Perennial Celery Plant?

A few years ago, my neighbor gave me a portion of root from a perennial plant she called a "celery herb". It grows very well in partial or direct sunlight, tolerates drought and light frost. The mature plant I have in my kitchen herb garden is now about 18 inches across the base and every year grows a mass of stalks with leaves that do closely resemble celery although the stalks are more tubular. The flavor and aroma are very like celery. The dried leaves retain their color and flavor well, and I have used it occasionally for flavoring soups and stews, although I am hesitant to use it as extensively as I might because I don't really know what it is or what other properties or health effects it may have. Are you familiar with this plant or able to identify it?

It sounds very much like lovage. You can read more about it in our online catalogue, as we offer seeds and plants for this plant.
Lovage can reach 2 metres (6 feet) or more in height, though first or second year plants are shorter. It is very easy to grow, and very hardy.
The flavour and aroma definitely suggests celery, but the flavour is sweeter and stronger. In central Europe it commonly used in soups and stews, and is often recommended in vegetarian soups in place of a stock. It is often known by the name, "maggi" or "maggi plant".