Vitus 980 and bridges tangs indicate a high end frame. The combination of brake tunnels, bottle bosses, exposed caliper nuts and cables routed over the BB shell suggest early 1980s. Given the era, it likely employs French threading and metric size tubing. Parallel angles and dropout eyelets, in conjunction with the apparent era, suggest a non-competition model.
The frame is underdressed, with components not worthy of it's level, particularly the swaged crankset and upper entry level Simplex SX410 derailleurs. The brakeset is lower mid-range, 1st generation, Shimano 105 (aka Golden Arrow). I strongly suspect none of the components are OEM. It may have have been bought as a frameset and built up from a donor bicycle,with a change in brakes.
As noted, it is a Lapierre, a smaller French brand which was founded shortly after World War II and was family owned until being taken over by the Accell group in the mid-1990s. Accell grew the brand and it is now much more widely known, even sponsoring a pro team. You've acquired a relatively rare and nice frameset. Enjoy.
Last edited by T-Mar; 10-24-17 at 06:09 AM.