I love postcrossing (Russia 2015)

First Day Cover I love postcrossing it reflects the thematic directions:

The mail or post is a system for physically transporting documents and other small packages; or, the postcards, letters, and parcels themselves. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century national postal systems have generally been established as government monopolies with a fee on the article prepaid. Proof of payment is often in the form of adhesive postage stamps, but postage meters are also used for bulk mailing. Modern private postal systems are typically distinguished from national postal agencies by the names "courier" or "delivery service". Postal authorities often have functions other than transporting letters. In some countries, a postal, telegraph and telephone (PTT) service oversees the postal system, in addition to telephone and telegraph systems. Some countries' postal systems allow for savings accounts and handle applications for passports.

A monument is a type of structure that was explicitly created to commemorate a person or event, or which has become relevant to a social group as a part of their remembrance of historic times or cultural heritage, due to its artistic, historical, political, technical or architectural importance. Examples of monuments include statues, (war) memorials, historical buildings, archaeological sites, and cultural assets. If there is a public interest in its preservation, a monument can for example be listed as a UNESCO World Heritage Site. The Palgrave Encyclopedia of Cultural Heritage and Conflict gives the next definition of monument:

Architecture (Latin architectura, from the Greek ἀρχιτέκτων arkhitekton "architect", from ἀρχι- "chief" and τέκτων "builder") is both the process and the product of planning, designing, and constructing buildings and other physical structures. Architectural works, in the material form of buildings, are often perceived as cultural symbols and as works of art. Historical civilizations are often identified with their surviving architectural achievements.

A globe is a spherical model of Earth, of some other celestial body, or of the celestial sphere. Globes serve purposes similar to maps, but, unlike maps, they do not distort the surface that they portray except to scale it down. A model globe of Earth is called a terrestrial globe. A model globe of the celestial sphere is called a celestial globe