It is rather curious that there are two tentative submissions for Lisbon, dated with the same exact day, of which one happens to entirely encompass the other. Pombaline Lisbon is a smaller area within the boundaries of the Historic Lisbon tentative site; even the text of submissions repeats the same facts and claims in many instances. When you are in the heart of the Portuguese capital, you are basically visiting two TWH sites at once, although I find it pretty obvious that they will never become two distinct WH sites.
The term Pombaline refers to Marquis of Pombal who led the reconstruction of central Lisbon after the devastating earthquake of 1755. The resulting complex, while undoubtedly innovative for its times, has a measure of uniformity and muted visual impact. Throughout Lisbon, building façades are largely flat and, while varying in color and occasionally covered by tiles, are mostly devoid of decorative elements aside from narrow balconies. Signs of neglect or at best of unenthusiastic upkeep are found frequently. And there isn’t really anything that could be called an unmissable iconic sight. Praça do Comércio may be the most well-known image, although there are several open squares in the Baixa Pombalina neighborhood that are worth strolling around. Baixa Pombalina is also the lowest-lying and the flattest part of Lisbon, which only magnifies the aforementioned uniformity.
Unless you decide to join the line for Elevador de Santa Justa (I much more prefer the top of the Arch of Rua Augusta, btw) or linger at the waterfront on Terreiro de Paço or sit down for a lunch at one of the tourist traps along on a pedestrian street, you are likely to get your fill of the area in a matter of an hour-plus.
I liked what I saw in Lisbon in general, and I think the larger nomination should one day become a full WHS. Pombaline part, on its own, falls a bit short in my eyes.