Answer: You must have an absolutely wonderful plant! Perhaps it is a specimen of the famous "Persian Yellow" (Rosa foetida persiana) which has been grown in gardens since at least 1837. This plant has fragrant double flowers in clusters for about a month in the spring.
If the plant seems healthy and happy, then you might not want to do anything different to it at all. If on the other hand you can see dead branches or stems, go ahead and remove those. Based on your description it sounds like you have an old fashioned shrub rose growing on its own roots. This type of rose usually does not require much pruning except as described above and then possibly to thin it out a bit to encourage vigorous new growth. To do this, reach far into the plant and remove a few of the oldest stems as close to the ground as possible. If you do this every year eventually you will have renewed the entire plant.
Q&A Library Searching Tips