the returned coordinates are weird:
curl "http://nominatim.openstreetmap.org/search?format=json&limit=10&addressdetails=0&q=Bremen&polygon=1"
[{"place_id":"97588446","licence":"Data \u00a9 OpenStreetMap contributors, ODbL 1.0. http://www.openstreetmap.org/copyright","osm_type":"relation","osm_id":"62559","boundingbox":["53.0110359191895","53.598274230957","8.48159217834473","8.99058246612549"],"polygonpoints":[["9.5499311","49.5667319"],["9.5522563","49.5679922"],["9.5518217","49.5689302"],["9.5540179","49.5694915"],["9.5564399","49.5694981"],["9.5580905","49.5694153"],["9.5584269","49.5697253"],["9.5586898","49.5700091"],["9.5590882","49.5698707"],["9.5604949","49.5699702"],["9.5616632","49.5695635"],["9.5607102","49.569066"],["9.5610369","49.5675352"],["9.5577971","49.5679002"],["9.5578046","49.5668186"],["9.5558284","49.5665107"],["9.5559142","49.5662236"],["9.555117","49.5662247"],["9.5544539","49.565937"],["9.5533457","49.5668645"],["9.5527198","49.5666703"],["9.5505432","49.5656852"],["9.5499311","49.5667319"]],"lat":"53.0758099","lon":"8.80717","display_name":"Bremen, HB, Deutschland, European Union","class":"boundary","type":"administrative","importance":0.763036457778,"icon":"http://nominatim.openstreetmap.org/images/mapicons/poi_boundary_administrative.p.20.png"},{"place_id":"97950782","licence":"Data \u00a9 OpenStreetMap contributors, ODbL 1.0. http://www.openstreetmap.org/copyright","osm_type":"relation","osm_id":"62718","boundingbox":["53.0110359191895","53.6101875305176","8.48159217834473","8.99058246612549"],"polygonpoints":[["-86.174688","41.451801"],["-86.17463","41.452257"],["-86.174542","41.452729"],["-86.174469","41.452987"],["-86.174381","41.45319"],["-86.174364","41.45328"],["-86.171216","41.453116"],["-86.1706753","41.453088"],["-86.165223","41.452729"]....
curl "http://nominatim.openstreetmap.org/search?format=json&limit=10&addressdetails=0&q=Bremen&polygon_geojson=1"
[{"place_id":"97588446","licence":"Data \u00a9 OpenStreetMap contributors, ODbL 1.0. http://www.openstreetmap.org/copyright","osm_type":"relation","osm_id":"62559","boundingbox":["53.0110359191895","53.598274230957","8.48159217834473","8.99058246612549"],"lat":"53.0758099","lon":"8.80717","display_name":"Bremen, HB, Deutschland, European Union","class":"boundary","type":"administrative","importance":0.763036457778,"icon":"http://nominatim.openstreetmap.org/images/mapicons/poi_boundary_administrative.p.20.png","geojson":{"type":"MultiPolygon","coordinates":[[[[8.4815929,53.2264612],[8.4821438,53.2265521],[8.4829347,53.2267185],[8.4843095,53.2270101],[8.4857372,53.2273151],[8.487138,53.227597],[8.4883678,53.22788],[8.4885416,53.2279264],[8.4886508,53.22796],[8.4888737,53.228208],[8.4894747,53.22809],[8.4895406,53.22796],[8.4894937,53.227739],[8.4894587,53.227575],[8.4894917,53.2268611],[8.4895787,53.2267011],[8.4897386,53.2266402],[8.4900386,53.2266781],[8.4909384,53.2267961],[8.4913354,53.2268461],[8.4915983,53.2268761]....