that really hurts, you know. >> our correspondent christophe putzel on the street of new york city. >ial issues and what artists have to say with them. what does a grammy winning puerto rican group and juliana sang have i julianjulian assange have in common? take a look. ♪ your weapons reveal your fears for all to see ♪ ♪ from cairo to quito, the power of the people armed with the truth ♪ ♪ >> well, joining us from san juan puerto rico, and edwardo martinez, also known as visicante. we'll try to figure out why you got those names to begin with, us. this is quite a collaboration that you guys put together. you guys already significant artists but also tom morello. >> it's a great collaboration not only julian assange, you have from palestine and israel, it's a song we wrote with the people using their words and their voices. >> you really crowd-sourced this, you i understand crowd-sourced your ideas on twitter? >> yeah, we used twitter and all the web media to -- in order to write this song and do the whole song. and at the end, we decide to shoot it in palestine. and it was very inter

the story behind these great and brilliant works, here is america tonight's christophe putzel. >> the new york public library, grand central terminal, the national history museum in washed. these iconic buildings have a secret. to discover what it is, you have to look up. these vaulted buildings were designed by a father and son, they're method sparked a revolution in architecture. >> it was almost as if they were dropped here from the 14th century into early 20th century u.s. in building some of the greatest buildings our country has ever known. this is really an immigrant story of the unflamed talented master craftsmen who made our great country, made you are our grade buildings possible but haven't been celebrate. >> in 1881. rafael tbvmentuastavino and his son brought an old worl masonry technique. >> it was fire proof, it was incredibly strong. and it could be built with no support from below during construction. almost like magic. >> we're right between the outer dome and the inner dome. unbelievably thin, four inches thick. >> just four inches? >> yep, remarkably thin. >> yarda

our correspondent christophe putzel tours the exhibit dedicated to their work. you'll be surprised as how many of those are in our everyday lives. that's coming up at the top of the hour on america tonight, tony. joie, we appreciate it, see you then. >>> kwanzaa was initially an attempt to celebrate pan africa unity. we don't know how many people actually celebrate there holiday, but it still remains a part of the american holiday season. let's talk kwanzaa. professor, it is good to see you, it is good to talk to you. do you celebrate kwanzaa? the reason i ask you is, i don't. i'm not sure why i don't. >> no, i don't celebrate kwanz kwanzaa. it was mostly during childhood, pretty haphazardly. i know people who celebrate kwanzaa. >> what do you think of the celebrations? >> i find it an incredibly beautiful ceremony. it is a secular holiday, it is an integration of incredibly beautiful values. all of the gifts are supposed to be hand made, nonmaterialistic holiday, the are foundations of this holiday are supposed to be self-determination, ethics and values. >> le