Interferometry is at the heart of wave optics. For a long time interferometers were only realizable on the macroscale, however, with the miniaturization of the optical technology, the possibility of realizing microscale interferometers arose. Recent developments towards two-dimensional (2D) optics show that surface plasmons (SPs), which are quasi-2D electro- magnetic modes confined at the interface between a dielectic and a metal [1], can interfere and generates fringes [2, 3]. With SPs, unlike in conventional optics, it becomes imaginable to realize highly integrated optical planar devices, allowing one to overcome the classical diffraction limit. The application of SPs to interferometry experiments with micrometer sized devices has been recently exploited for demonstrating a MachZehnder configuration [4], which constituted a first step for the implementation of SP wave optics. In this letter, we extend this precedent work to demonstrating an optical corral for SP waves, by using an elliptical Bragg reflector. In such an elliptical corral, acting as an interferometer, we gener- ate stationary waves by launching a SP in one focal point F 1 , to be focused in the other one F 2 . We describe the observed interferences and SP focalization inside the elliptical corral, and we compare our observations with a simple numerical model. In order to achieve a significant SP reflectivity and to reduce SP scattering to light we used in Ref. 4 a mirror composed of protrusions on a silver thin film, arranged in parallel lines. To obtain a reflectivity better that 90% we worked in the Bragg regime [5], depending strongly on the SP wavelength lSP, the separation distance between the protrusions lines, and the incidence angle. However, the Bragg conditions cannot be fulfilled for all directions that appear in a diverging beam. In an elliptical corral, however, the length of all SP paths connecting the two foci F 1 , 2 to any point on the mirror equals 2 a , i.e., the long axis length. It is thus straightforward to realize Braggs condition by using confocal ellipses. Construc- tive interference between the reflected contributions of the different ellipses will be present only if the variation δ (2 a ) of the long axis length between two concentric ellipses is equal to Nλ$_{SP}$ , where N is an integer. As this condition is independent of angle the Bragg reso- nance is easy to obtain even with divergent SP beams. This property constitutes one of the essential motivations for elaborating an elliptical interferometer. The SP optical elements are obtained by the same electron beam lithography method as described in Ref. 4. The elements, as sketched in Fig. 1(a), are composed of SiO 2 protrusion (160 nm diameter, 80 nm height, center-to-center distance 250 nm), deposited on a glass substrate and covered by a layer of gold of 80 nm thickness. The protrusions are arranged in five confocal ellipses, 2