Subject of the expression of interest: The LEGEND-1000 experiment (www.legend-exp.org) will operate 1000 kg of germanium detectors in a 200 m^3 liquid argon cryostat at the Italian Gran Sasso laboratory (www.lngs.infn.it). LNGS maintains 3 large halls (18 m x 18 m x 100 m) under the Gran Sasso mountain. Access is via the A24 highway tunnel connecting Termo to L'Aquila with an exit in the tunnel. The Max Planck Institute for Nuclear Physics (MPIK) is responsible for the cryostat. The cryostat has an outer diameter of 7 m and a height of 10 m. It is a pressure vessel that has to be constructed underground according to PED 2014/68/EU following the requirements of EN 13445. The entrance door to the halls (4 m wide and 4.5 m high) limits the size of the parts that can be shipped. MPIK is searching for a company with experience in the construction of pressure vessel of similar size and with experience of remote-site mounting and welding. The tender documentation give more details about the project, LNGS and the cryostat. Interested companies have to visit LNGS before preparing an offer to understand the boundary conditions. The project is subject to funding approval. Information via: https://mcloud.mpi-hd.mpg.de/index.php/s/dydCd4rZ6FkwEgE