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the eclipsing binary systems containing classical cepheids are very rare . although we know tens of binary cepheids in our galaxy ( e.g. evans  @xcite ) , none is an eclipsing system . however extensive search for variability in microlensing surveys in magellanic clouds resulted in reporting of reliable eclipsing binary candidates : a double cepheid system macho 05:21:54.8 - 69:21:50 ( alcock  @xcite ) , first overtone cepheid ogle lmc sc16 119952 ( udalski  @xcite ) and two fundamental mode cepheids ogle - lmc - cep-0227 and ogle - lmc - cep-1812 ( soszyski  @xcite ) . deriving fundamental physical parameters of classical cepheids is an important task regarding their great significance for extragalactic distance scale . as part of the araucaria project we made follow up of candidate eclipsing binaries in the large magellanic cloud ( lmc ) . this allowed us to confirm first known eclipsing binary cepheid ( pietrzyski  @xcite ) and to resolve so called the mass discrepancy problem in a favour of cepheid pulsation models . our goals are summarised as follow : 1 ) determination of accurate dynamical masses of classical cepheids ; 2 ) verification of the mean cepheid radius - pulsation period relation ; 3 ) developing of a consistent scheme for solving light and radial velocity curves of radially pulsating star in an eclipsing binary system ; 4 ) determination of distance independent the projection factor for cepheids ; 5 ) analysis of the limb darkening dependence on a pulsation phase . below we presented some results and details of our cepheids research . the sections are devoted to particular eclipsing binary systems . the figure  [ fig1 ] presents position of our target eclipsing binary cepheids within the lmc body . this relatively bright star ( v = 15.2 mag ) was discovered to be a classical fundamental mode cepheid by soszyski  ( @xcite ) . in the same paper the cepheid was mentioned as possible eclipsing binary candidate . we confirmed it to be an eccentric double lined binary with orbital period of 309 days and deep eclipses ( pietrzyski  @xcite ) . we derived physical parameters of both components and , especially , their precise masses . subsequently we performed extensive optical and near infrared photometric and spectroscopic monitoring of this star to improve our solution . to this end we developed a novel method of light curve and radial velocity curve analysis . the new code and data allowed us to put stringent limits onto cepheid physical parameters ( pilecki  @xcite ) . the quality of the fit is illustrated in fig . [ fig2 ] .    derived masses and radii are fully consistent with a solution reported by pietrzyski  ( @xcite ) but by a factor of two more precise . we detected anomalously large limb darkening in the pulsating component in disagreement with predictions from static atmosphere models . for more we calculated the projection factor of this cepheid which is an important parameter in baade - wesselink type methods of distance determination to radially pulsating stars . this direct determination is a distance and a limb darkening independent what differs our result from those obtained for galactic cepheids from interferometry ( e.g.  mrand  @xcite ) . the value we obtained remain in agreement with some theoretical model predictions ( e.g.  nardetto  @xcite ) . fundamental parameters of the cepheid component are given in table  [ tab1 ] . the companion star has almost the same mass and luminosity like the cepheid . the star was confirmed to be an eccentric double lined eclipsing binary with an orbital period of 552 days by pietrzyski  ( @xcite ) . the pulsating component is a fundamental mode classical cepheid having shorter pulsation period than cep-0227 - see table  [ tab1 ] . however during analysis of this system we detected non - negligible third light . first hint of it came from spectroscopy as we observed an additional peak in the broadening function power distribution - fig . the peak is not observed on all spectra suggesting that the third light comes from an optical blend . in our analysis we assumed that the light contribution from this blend is about 10% of the total flux in i - band . the presence of the optical blend(s ) was confirmed later through hst multicolour imaging . as the orbital inclination of the system is very close to 90 degrees the presence of the third light does not affect significantly masses reported by pietrzyski  ( @xcite ) . thus the cepheid component is only the second one with mass known with accuracy better than 3% . however radii and luminosities of both component are a subject of some uncertainty up to 5 - 10% . this system is somewhat puzzling because the cepheid has much larger mass ( and luminosity ) than the companion star , however we meet both these stars in a short evolutionary phase of giant evolution . currently we work on improving our previous solution and deriving the p - factor for this cepheid . this star contains a first overtone cepheid in a eccentric double lined eclipsing system having an orbital period of 800 days . we confirm here that both stars are gravitationally bounded by detecting their mutual orbital motion - see fig  [ fig4 ] . because of the eccentricity and a position of the orbit we observe only one minimum in this system when a red giant companion is eclipsing the cepheid star . our photometric campaign to detect secondary minimum around expected orbital phase 0.55 gave null result . it is interesting that the companion star is in fact more massive and more luminous than the cepheid . star lmc562.05.9009 is reported by soszyski  @xcite as candidate eclipsing binary cepheid based on results from the gaia south ecliptic pole search by ogle - iv survey . the cepheid star pulsates in fundamental mode . we monitor this star extensively with spectroscopy and photometry . up to now we observed only two deep eclipses of comparable depth ( primary and secondary minimum ) and thus we can not calculate orbital period . we collected some spectra which show two strong peaks in the broadening function power ( fig . [ fig5 ] ) suggesting that this is a true binary . star lmc506.14.8910 was found to be a candidate eclipsing binary cepheid during search for variable stars in ogle - iv survey . the cepheid also pulsates in fundamental mode , however eclipses are shallow . especially we see only a trace of a possible secondary eclipse at orbital phase 0.53 - see fig . [ fig5 ] . at the moment we have no information about a presence of a companion star in spectra . .physical parameters of the lmc classical cepheids in eclipsing binaries [ cols="^,>,>,>,>,>",options="header " , ]     _ notes : _ + @xmath0 assuming the orbital inclination of 90 deg . + @xmath1 ? - not directly determined yet . during a few last years we were able to significantly improve the knowledge about physical parameters of classical cepheids by observing and analysing two eclipsing binary cepheids in the lmc . at least one more eclipsing binary system ogle-2532 is confirmed . our future plans consist of 1 ) performing similar analysis for cep-1812 like we did in the case of cep-0227 , 2 ) follow up of two new candidate eclipsing binaries , 3 ) confirmation of binary nature of double eclipsing cepheid ogle - lmc - cep-1718 and 4 ) improving our understanding of the baade - wesselink method applied for cepheids . we gratefully acknowledge financial support for this work from the polish national science center grant maestro dec-2012/06/a / st9/00269 .    99 alcock , c. , ( macho ) 1995 , aj , 109 , 1653 evans , r. n. , bond , h. e. , schaefer , g. h. , mason , b. d. , karovska , m. and tingle , e. 2013 , aj , 146 , 93 mrand , a. , kervella , p. , coud de foresto , v. 2005 , a&a , 439 , l9 nardetto , n. , gieren , w. , kervella , p. , 2009 , a&a , 502 , 951 pietrzyski , g. , thompson , i. b. , gieren , w. , graczyk , d. , bono , g. , 2010 , nature , 468 , 542 pietrzyski , g. , thompson , i. b. , graczyk , d. , gieren , w. , pilecki , b. , udalski , a. , soszyski , i. , bono , g. , konorski , p. , nardetto , n. and storm , j. 2011 , apj , 742 , 20 pilecki , b. , graczyk , d. , pietrzyski , g. , gieren , w. , thompson , i. b. , 2013 , to appear in mnras , arxiv:1308.5023 pojmaski , g. 2002 , acta astron . , 52 , 397 soszyski , i. , udalski , a. , szymaski , m. k. , kubiak , m. , pietrzyski , g. , wyrzykowski ,  . , szewczyk , o. , ulaczyk , k. & poleski , r. 2008 , acta astron . , 58 , 293 soszyski , i. , udalski , a. , poleski , r. , et al . 2012 , acta astron . , 62 , 219 udalski , a. , soszyski , i. , szymaski , m. , kubiak , m. , pietrzyski , g. , woniak , p. , and ebru , k. 1999 , acta astron .
the status of our work on binary classical cepheid systems in the large magellanic cloud is presented . 
 we report on results from our follow up of two eclipsing binary cepheids ogle - lmc - cep-0227 and ogle - lmc - cep-1812 . here 
 we presented for the first time confirmation that a third cepheid ogle - lmc - cep-2532 is a true eclipsing binary cepheid with a period of 800 days . 
 two other very good candidates for eclipsing binaries detected during ogle - iv survey are also discussed .