📜4️⃣📅

#leap year #4 year cycle #calendar reform #historical calendar #ancient calendar

🗓️🔄4️⃣0️⃣0️⃣☀️

#gregorian calendar #leap year cycle #calendar reform #400 year cycle #solar calendar

📅🇻🇦🕿️

#gregorian calendar #pope gregory xiii #vatican #calendar reform #year #date system

🎄📜🇻🇦

#gregorian calendar #pope gregory xiii #calendar reform

📅🇻🇦✝️

#pope gregory #gregorian calendar #calendar reform #vatican #pope #catholic church

🇻🇦📜📅

#pope gregory xiii #papal bull #inter gravissimas #calendar reform #catholic church #1582

1️⃣3️⃣🈷️🗓️

#13 month calendar #calendar reform #international fixed calendar #extra month #yearly calendar